Structural framework for wireless charging mats

ABSTRACT

Embodiments describe a wireless charging device including: a housing having a charging surface and first and second walls that define an interior cavity; a transmitter coil arrangement disposed within the interior cavity, an interconnection structure positioned within the interior cavity below the transmitter coil arrangement, the interconnection structure including a plurality of packaged electrical components mounted on the interconnection structure and configured to operate the plurality of transmitter coils during wireless power transfer, where the plurality of packaged electrical components is located below the transmitter coil arrangement; and a frame comprising a plurality of openings positioned corresponding to the plurality of packaged electrical components, each opening providing space within which a respective packaged electrical device is disposed.

CROSS REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 62/399,243, filed on Sep. 23, 2016, U.S. Provisional PatentApplication No. 62/399,245, filed on Sep. 23, 2016, U.S. ProvisionalPatent Application No. 62/399,248, filed on Sep. 23, 2016, U.S.Provisional Patent Application No. 62/399,255, filed on Sep. 23, 2016,U.S. Provisional Patent Application No. 62/399,259, filed on Sep. 23,2016, U.S. Provisional Patent Application No. 62/399,263, filed on Sep.23, 2016, U.S. Provisional Patent Application No. 62/399,269; filed onSep. 23, 2016, U.S. Provisional Patent Application No. 62/399,273, filedon Sep. 23, 2016, U.S. Provisional Patent Application No. 62/399,276;filed on Sep. 23, 2016, and U.S. Provisional Patent Application No.62/526,905; filed on Jun. 29, 2017, the disclosures of which are herebyincorporated by reference in their entirety and for all purposes.

BACKGROUND

Electronic devices (e.g., mobile phones, media players, electronicwatches, and the like) operate when there is charge stored in theirbatteries. Some electronic devices include a rechargeable battery thatcan be recharged by coupling the electronic device to a power sourcethrough a physical connection, such as through a charging cord. Using acharging cord to charge a battery in an electronic device, however,requires the electronic device to be physically tethered to a poweroutlet. Additionally, using a charging cord requires the mobile deviceto have a connector, typically a receptacle connector, configured tomate with a connector, typically a plug connector, of the charging cord.The receptacle connector typically includes a cavity in the electronicdevice that provides an avenue within which dust and moisture canintrude and damage the device. Furthermore, a user of the electronicdevice has to physically connect the charging cable to the receptacleconnector in order to charge the battery.

To avoid such shortcomings, wireless charging devices have beendeveloped to wirelessly charge electronic devices without the need for acharging cord. For example, some electronic devices can be recharged bymerely resting the device on a charging surface of a wireless chargingdevice. A transmitter coil disposed below the charging surface mayproduce a time-varying magnetic field that induces a current in acorresponding receiving coil in the electronic device. The inducedcurrent can be used by the electronic device to charge its internalbattery.

Some existing wireless charging devices have a number of disadvantages.For instance, some wireless charging devices require an electronicdevice to be placed in a very confined charging region on the chargingsurface in order for the electronic device being charged to receivepower. If an electronic device is placed outside of the charging region,the electronic device may not wirelessly charge or may chargeinefficiently and waste power. This limits the ease at which anelectronic device can be charged by the wireless charging device.

SUMMARY

Some embodiments of the disclosure provide a wireless charging devicethat includes a charging surface having a broad charging region uponwhich an electronic device can be placed to wirelessly receive power. Insome embodiments the wireless charging device can be a wireless chargingmat that includes an arrangement of wireless power transmitters beneaththe charging surface defining a charging region. The wireless chargingmat allows the electronic device to be charged at any location withinthe charging region, thereby increasing the ease at which electronicdevices can be charged by the mat.

In some embodiments a wireless charging device includes: a housinghaving a charging surface and first and second walls that define aninterior cavity; a transmitter coil arrangement disposed within theinterior cavity, the transmitter coil arrangement including a pluralityof transmitter coils positioned within the interior cavity in anoverlapping arrangement such that different coils in the plurality ofcoils are on different planes and each of the plurality of transmittercoils has a central axis positioned a lateral distance away from thecentral axes of all other transmitter coils of the plurality oftransmitter coils; an interconnection structure positioned within theinterior cavity below the transmitter coil arrangement, theinterconnection structure including a plurality of packaged electricalcomponents mounted on the interconnection structure and configured tooperate the plurality of transmitter coils during wireless powertransfer, where the plurality of packaged electrical components islocated below the transmitter coil arrangement; and a frame comprising aplurality of openings positioned corresponding to the plurality ofpackaged electrical components, each opening providing space withinwhich a respective packaged electrical device is disposed.

In some additional embodiments, a wireless charging device includes: ahousing having a planar charging surface and first and second shellsthat define an interior cavity; a transmitter coil arrangement disposedwithin the interior cavity, the transmitter coil arrangement including aplurality of transmitter coils positioned within the interior cavity inan overlapping arrangement such that different coils in the plurality ofcoils are on different planes each of the plurality of transmitter coilshas a central axis positioned a lateral distance away from the centralaxes of all other transmitter coils of the plurality of transmittercoils; an interconnection structure positioned within the interiorcavity below the transmitter coil arrangement, the interconnectionstructure including a plurality of packaged electrical componentsmounted on the interconnection structure and configured to operate theplurality of transmitter coils during wireless power transfer, where theplurality of packaged electrical components is located below thetransmitter coil arrangement; a frame comprising a plurality of openingspositioned corresponding to the plurality of packaged electricalcomponents, each opening providing space within which a respectivepackaged electrical device is disposed; and a bottom shield disposedbelow and coupled to the frame, the bottom shield including a shieldinglayer and one or more insulating layers, where the one or moreinsulating layers are positioned to correspond with at least one openingof the plurality of openings.

In some further additional embodiments, a wireless charging systemincludes: an electrical device comprising a receiver coil configured togenerate a current to charge a battery when exposed to a time-varyingmagnetic flux; and a wireless charging device configured to generate thetime-varying magnetic flux to wirelessly charge the electronic device.The wireless charging device includes: a housing having a chargingsurface, the housing including first and second walls that define aninterior cavity; a transmitter coil arrangement disposed within theinterior cavity, the transmitter coil arrangement including a pluralityof transmitter coils positioned within the interior cavity in anoverlapping arrangement such that different coils in the plurality ofcoils are on different planes and each of the plurality of transmittercoils has a central axis positioned a lateral distance away from thecentral axes of all other transmitter coils of the plurality oftransmitter coils; an interconnection structure positioned within theinterior cavity below the transmitter coil arrangement, theinterconnection structure including a plurality of packaged electricalcomponents mounted on the interconnection structure and configured tooperate the plurality of transmitter coils during wireless powertransfer, where the plurality of packaged electrical components arelocated below the transmitter coil arrangement; and a frame comprising aplurality of openings positioned corresponding to the plurality ofpackaged electrical components, each opening providing space withinwhich a respective packaged electrical device is disposed.

A better understanding of the nature and advantages of embodiments ofthe present invention may be gained with reference to the followingdetailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified diagram illustrating an exemplary wirelesscharging mat and two devices positioned on the charging mat, accordingto some embodiments of the present disclosure.

FIG. 2 is a simplified diagram illustrating a transmitter coilarrangement embedded within a charging mat, according to someembodiments of the present disclosure.

FIG. 3 is a simplified diagram illustrating an exemplary base patternhaving three transmitter coils, according to some embodiments of thepresent disclosure.

FIG. 4 is a simplified diagram illustrating an exemplary transmittercoil arrangement configured in a rosette pattern, according to someembodiments of the present disclosure.

FIGS. 5A-5C are simplified diagrams illustrating the different layers ofa transmitter coil arrangement configured in a rosette pattern,according to some embodiments of the present disclosure.

FIGS. 6A-6E are simplified diagrams illustrating an expansion of apattern of transmitter coils, according to some embodiments of thepresent disclosure.

FIGS. 7A-7C are simplified diagrams and charts illustrating theformation of a continuous charging surface, according to embodiments ofthe present disclosure.

FIG. 8A is a simplified diagram illustrating exemplary radial directionsfor two transmitter coils, according to some embodiments of the presentdisclosure.

FIG. 8B is a simplified diagram illustrating an exemplary transmittercoil arrangement formed of three transmitter coil layers where thetransmitter coils of each layer is arranged in a different radialdirection than the other layers, according to some embodiments of thepresent disclosure.

FIGS. 9A-9C are simplified diagrams illustrating different transmittercoil layers of the transmitter coil arrangement illustrated in FIG. 8B,according to some embodiments of the present disclosure.

FIG. 10 is a simplified diagram illustrating an exemplary transmittercoil arrangement where transmitter coils are arranged in differentradial directions based on their position in the transmitter coilarrangement, according to some embodiments of the present disclosure.

FIGS. 11A-11C are simplified diagrams illustrating different transmittercoil layers of the transmitter coil arrangement illustrated in FIG. 10,according to some embodiments of the present disclosure.

FIG. 12A is a simplified diagram illustrating an exemplary transmittercoil arrangement where all transmitter coils have substantially the samedimensions than other transmitter coils in the transmitter coilarrangement, according to some embodiments of the present disclosure.

FIG. 12B is a simplified diagram illustrating an exemplary transmittercoil arrangement where one or more transmitter coils have differentdimensions than other transmitter coils in the transmitter coilarrangement, according to some embodiments of the present disclosure.

FIG. 13A is a simplified diagram illustrating an exemplary coil of wireformed of a plurality of thin wires, according to some embodiments ofthe present disclosure.

FIG. 13B is a simplified diagram illustrating a cross-sectional view ofa single turn of a coil of wire formed of a plurality of thin wires,according to some embodiments of the present disclosure.

FIG. 13C is a simplified diagram illustrating an exemplary coil of wireformed of a single core of conductive wire, according to someembodiments of the present disclosure.

FIG. 13D is a simplified diagram illustrating a cross-sectional view ofa single turn of a coil of wire formed of a single core of conductivewire, according to some embodiments of the present disclosure.

FIG. 14A is a simplified diagram illustrating a top perspective view ofa coil of wire with termination ends positioned within an internaldiameter of the coil of wire and arranged at an angle with respect toone another, according to some embodiments of the present disclosure.

FIG. 14B is a simplified diagram illustrating a side view of the coil ofwire illustrated in FIG. 14A, according to some embodiments of thepresent disclosure.

FIG. 14C is a simplified diagram illustrating a top perspective view ofa coil of wire with termination ends positioned within an internaldiameter of the coil of wire and arranged parallel to one another,according to some embodiments of the present disclosure.

FIGS. 15A-15D are simplified diagrams illustrating top and side views ofan exemplary bobbin, according to some embodiments of the presentdisclosure.

FIGS. 16A and 16B are simplified diagrams illustrating top and bottomperspective views of an exemplary angle transmitter coil, according tosome embodiments of the present disclosure.

FIG. 17A is a simplified diagram illustrating an exemplary transmittercoil arrangement formed with angle transmitter coils, according to someembodiments of the present disclosure.

FIG. 17B is a simplified diagram illustrating a zoomed-in, bottomperspective view of a portion of an exemplary transmitter coilarrangement formed with angle transmitter coils, according to someembodiments of the present disclosure.

FIGS. 18A-18B are simplified diagrams illustrating top and bottomperspective views of an exemplary parallel transmitter coil, accordingto some embodiments of the present disclosure.

FIG. 19 is a simplified diagram illustrating an exemplary transmittercoil arrangement formed with parallel and angle transmitter coils,according to some embodiments of the present disclosure.

FIG. 20A is a simplified diagram illustrating an exploded side-viewperspective of a transmitter coil arrangement, according to someembodiments of the present disclosure.

FIG. 20B is a simplified diagram illustrating side-view perspective ofan assembled transmitter coil arrangement, according to some embodimentsof the present disclosure.

FIG. 21 is a simplified diagram illustrating an exemplary transmittercoil without a bobbin, according to some embodiments of the presentdisclosure.

FIG. 22A is a simplified diagram illustrating an exemplary transmittercoil arrangement formed of transmitter coils without bobbins, accordingto some embodiments of the present disclosure.

FIG. 22B is a simplified diagram illustrating an exemplary transmittercoil arrangement formed of transmitter coils without bobbins and withsimilarly organized termination ends, according to some embodiments ofthe present disclosure.

FIGS. 22C-22E are simplified diagrams illustrating individual layers ofan exemplary transmitter coil arrangement shown in FIGS. 22B and 22C,according to some embodiments of the present disclosure.

FIG. 23 is a simplified diagram illustrating an exploded view of anexemplary wireless charging mat having transmitter coils with bobbins,according to some embodiments of the present disclosure.

FIG. 24 is a simplified diagram illustrating an exploded view of anexemplary wireless charging mat having transmitter coils withoutbobbins, according to some embodiments of the present disclosure.

FIG. 25A is a simplified diagram illustrating a top-view of an exemplaryelectromagnetic shield with a thin conductive border, according to someembodiments of the present disclosure.

FIG. 25B is a simplified diagram illustrating a top-view of an exemplaryelectromagnetic shield with a conductive border that extends to edges ofa transmitter coil arrangement, according to some embodiments of thepresent disclosure.

FIG. 26A is a simplified diagram illustrating a cross-sectional view ofa part of a faraday cage around a transmitter coil arrangement of apartially-formed wireless charging mat, according to some embodiments ofthe present disclosure.

FIG. 26B is a simplified diagram illustrating a close-up cross-sectionalview of an interface between a shielding body and a conductive border,according to some embodiments of the present disclosure.

FIGS. 27A and 27B are simplified diagrams illustrating an exemplarystandoff, according to some embodiments of the present disclosure.

FIGS. 28A and 28B are simplified diagrams illustrating an exemplarystandoff with hook structures, according to some embodiments of thepresent disclosure.

FIG. 29 is a simplified diagram illustrating an exemplary assembledtransmitter coil arrangement attached to an underlying driver board,according to some embodiments of the present disclosure.

FIG. 30 is a simplified diagram illustrating a bottom-view of a dropframe coupled to a driver board, according to some embodiments of thepresent disclosure.

FIG. 31 is a simplified diagram illustrating a top-down view of anexemplary bottom shield, according to some embodiments of the presentdisclosure.

FIG. 32 is a simplified diagram illustrating an exploded view of anexemplary wireless charging mat including more than one transmitter coilarrangement, according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

Embodiments of the disclosure describe a wireless charging mat where anelectronic device can be efficiently charged across a vast majority, ifnot an entire area, of a charging surface of the wireless charging mat.Arrays of transmitter coils disposed below the charging surface maygenerate time-varying magnetic fields capable of inducing current in areceiver of the electronic device or of a docking station with which theelectronic device is coupled.

The wireless charging mat may include multiple transmitter coil layers.Each layer can include an array of transmitter coils arranged in a gridpattern and configured to generate magnetic fields in a correspondinggrid pattern. Spaces between each transmitter coil in the layer may be a“dead zone,” i.e., a region where a magnetic field is not generated.Thus, the multiple transmitter coil layers can be arranged so that thereare minimal dead zones across a charging surface of the wirelesscharging mat. In some embodiments, the wireless charging mat includesthree transmitter coil layers where each layer is arranged to fill deadzones in the other two layers. For instance, magnetic fields generatedby coils in a first layer can fill in dead zones in the second and thirdlayers. Likewise, magnetic fields generated by coils in the second layermay fill in dead zones in the first and third layers; and magneticfields generated by coils in the third layer can fill in dead zones inthe first and second layers. Accordingly, the three transmitter coillayers can collectively generate magnetic fields that span across thecharging surface, thereby enabling an electronic device to be chargedacross a vast majority of the charging surface. Aspects and features ofembodiments of such a wireless charging mat are discussed in furtherdetail herein.

I. Wireless Charging Mat

FIG. 1 illustrates an exemplary wireless charging mat 100, according tosome embodiments of the present disclosure. Wireless charging mat 100can include a charging surface 102 upon which a device having a wirelesspower receiver can be placed upon to wirelessly charge its battery. Insome embodiments, charging surface 102 may be a region of a top surface104 of wireless charging mat 100 that spans across a vast majority, ifnot the entire area, of top surface 104. Time-varying magnetic fieldsgenerated by wireless charging mat 100 can propagate through regions oftop surface 104 within charging surface 102 and form a continuous regionwithin which devices can wirelessly receive power.

In some embodiments, devices can be placed in any location withincharging surface 102 to receive power. For instance, a first device 106can be positioned on a left side of wireless charging mat 100 withincharging surface 102 and receive power from wireless charging mat 100.And a second device, e.g., device 108, can be positioned on a right sideof wireless charging mat 100 within charging surface 102 to receivepower from wireless charging mat 100. It is to be appreciated that adevice placed anywhere within charging surface 102 can receive powerfrom wireless charging mat 100 according to embodiments of the presentdisclosure. In some embodiments, more than one device may be placed onwireless charging mat 100 to receive power. As an example, both devices106 and 108 may be concurrently placed on wireless charging mat 100 andsimultaneously receive power.

Devices 106 and 108 can be any suitable device configured to receivepower from wireless charging mat 100. For example, device 106 and/ordevice 108 can be a portable electronic device (e.g., a mobile phone, amedia player, an electronic watch, and the like), a docking station, oran accessory electronic device, each having a receiver coil configuredto receive power when exposed to magnetic fields produced by wirelesscharging mat 100.

Wireless charging mat 100 can be shaped to provide a suitable surfaceupon which one or more devices can be charged. For instance, wirelesscharging mat 100 can be in the shape of a pill (a generally oval shape)as shown in FIG. 1, although other embodiments can have differentshapes. Some embodiments can have a circular shape, rectangular shape,square shape, or any other suitable shape for providing a surface uponwhich a device can be wirelessly charged without departing from thespirit and scope of the present disclosure.

II. Arrangement of Transmitter Coils

Time-varying magnetic fields can be generated by multiple transmittercoils embedded within wireless charging mat 100. For instance, wirelesscharging mat 100 can include a transmitter coil arrangement as shown inFIG. 2. FIG. 2 illustrates transmitter coil arrangement 200 embeddedwithin charging mat 100, according to some embodiments of the presentdisclosure. The illustration of FIG. 2 shows wireless charging mat 100with top surface 104 removed so that the embedded transmitter coilarrangement 200 may be seen. Transmitter coil arrangement 200 caninclude multiple arrays of transmitter coils arranged in differentlayers and in a non-concentric fashion so that when all of thetransmitter coils are operating, an array of magnetic fields can begenerated across charging surface 102.

A. Transmitter Coil Patterns

According to some embodiments of the present disclosure, the specificarrangement of transmitter coils 200 enables wireless charging mat 100to generate an array of magnetic fields that forms a continuous chargingsurface upon which an electronic device can be charged. The continuouscharging surface allows an electronic device to be efficiently chargedat any location within the charging surface. The charging surface canspan across a vast majority, if not an entire area, of wireless chargingmat 100. In some embodiments, transmitter coil arrangement 200 can bearranged according to a base pattern that enables transmitter coilarrangement 200 to generate magnetic fields that form the continuouscharging surface. The base pattern can be expanded to form more complexpatterns that form a larger continuous charging surface.

1. Base Pattern

FIG. 3 illustrates an exemplary base pattern 300 having threetransmitter coils: first transmitter coil 302, second transmitter coil304, and third transmitter coil 306, according to some embodiments ofthe present disclosure. First, second, and third transmitter coils 302,304, and 306 can be arranged in three separate layers, thereby forming atransmitter coil stack. For example, first transmitter coil 302 can bepositioned in a first layer, second transmitter coil 304 can bepositioned in a second layer above the first layer, and thirdtransmitter coil 306 can be positioned in a third layer above the firstand second layers. Each transmitter coil can be formed of a single layerof wire that is wound from an outer radius to an inner radius so that itforms a flat, ring-like shape, as will be discussed in detail furtherherein. As shown in FIG. 3, each transmitter coil is shown without acentral member (e.g., a “bobbin” as will also be discussed furtherherein) so that other transmitter coils located in layers below thetransmitter coil can be seen for ease of understanding.

In some embodiments, first, second, and third transmitter coils 302,304, and 306 can each include a central termination zone. A centraltermination zone can be a region at the center of each transmitter coilthat is reserved for interfacing with an interconnection layer, such asa printed circuit board (PCB). As shown in FIG. 3, first, second, andthird transmitter coils 302, 304, and 306 can have central terminationzones 316, 318, and 320, respectively. Central termination zones 316,318, and 320 can be regions at the center of each transmitter coilreserved for interfacing with the interconnection layer, as will bediscussed further herein. Accordingly, first, second, and thirdtransmitter coils 302, 304, and 306 can be positioned in locations wheretheir respective central termination zones can interface with theinterconnection layer without being blocked by a neighboring transmittercoil. For instance, central termination zone 316 of transmitter coil 302is laterally positioned outside of the outer diameter of transmittercoil 304 and 306. The same can be said for central termination zones 318and 320. Accordingly, central termination zones 316, 318, and 320 canextend through the transmitter coil stack without intersecting anothertransmitter coil. In some embodiments, central termination zones 316,318, and 320 may be positioned equally spaced apart from one anothersuch that the central termination zones 316, 318, and 320 form anequilateral triangle 322.

2. Rosette Pattern

As mentioned above, the base pattern can be expanded upon to form otherpatterns for different shapes and sizes of wireless charging mats. Oneof such patterns is a rosette pattern, which may be suitable forsubstantially circular wireless charging mats given its circularprofile. The rosette pattern can be a pattern where the transmittercoils are arranged in an overlapping arrangement such that differentcoils in the plurality of coils are on different planes and arenon-concentric with each other. In an expanded base pattern, one or moretransmitter coil layers can include more than one transmitter coil.

FIG. 4 illustrates an exemplary transmitter coil arrangement 400configured in a rosette pattern, according to some embodiments of thepresent disclosure. Transmitter coil arrangement 400 can include threeseparate transmitter coil layers where one or more of those layersinclude multiple transmitter coils. For example, a first transmittercoil layer can include transmitter coils 402 a-c, a second transmittercoil layer can include transmitter coils 404 a-c, and a thirdtransmitter coil layer can include transmitter coil 406. Eachtransmitter coil in transmitter coil arrangement 400 can have an openingdefined by an inner diameter of the transmitter coil, where each openingincludes a termination zone 418 (i.e. central portion) that is notoverlapping any portion of an adjacent transmitter coil. Additionally,the transmitter coils are arranged such that no two coils in theplurality of coils are concentric with each other.

The base pattern may be pervasive throughout the rosette pattern suchthat every group of three transmitter coils, one in each transmittercoil layer, that are closest together is arranged in the base pattern.For instance, transmitter coils 402 a, 404 a, and 406 are arranged inthe base pattern. Likewise, transmitter coils 402 a, 404 b, and 406 arearranged in the base pattern, transmitter coils 404 b, 402 c, and 406are arranged in the base pattern, and so on and so forth. By arrangingtransmitter coil arrangement 400 according to the base pattern,transmitter coil arrangement 400 can create a continuous charging regionwithin which an electronic device can charge in any location.

To better understand the arrangement of an expanded base pattern, FIGS.5A-5C illustrate the different layers of transmitter coil arrangement400. Specifically, FIG. 5A illustrates the first layer includingtransmitter coils 402 a-c, FIG. 5B illustrates the second layerincluding transmitter coils 404 a-c, and FIG. 5C illustrates the thirdlayer including transmitter coil 406. According to embodiments,transmitter coils in the same layer can be equally spaced apart so thatthe generated magnetic fields can be arranged in an evenly spaced gridpattern. For example, transmitter coils 402 a-c and 404 a-c can bespaced apart by a distance D1. The distance D1 may be selected to bewide enough for parts of transmitter coils in other layers to fit withinit for stacking purposes, as will be discussed further herein. In otherembodiments, the distance D1 may be selected to be wide enough so thatadjacent transmitter coils do not make contact with each other. Forinstance, distance D1 may be less than 3 mm. In a particular embodiment,distance D1 is less than 1 mm.

The center of each transmitter coil in the same layer can be separatedby a distance D2. Distance D2 can affect the uniformity of magnetic fluxacross the charging surface. Larger distances D2 result in lowermagnetic flux uniformity across the charging surface, whereas smallerdistances D2 result in higher magnetic flux uniformity across thecharging surface. In some embodiments, distance D2 is selected to be thesmallest distance that allows for a suitable distance D1 betweentransmitter coils while taking into consideration the outer diameter ofeach transmitter coil. In additional embodiments, distance D2 is thesame for all adjacent transmitter coils in the same layer. Thus, groupsof three transmitter coils (e.g., transmitter coils 402 a-c and 404 a-cin each of the first and second layers, respectively) can be arrangedaccording to the end points of an equilateral triangle 422.

Although FIGS. 5A and 5B illustrate only three transmitter coils in asingle transmitter coil layer, it is to be appreciated that embodimentsare not limited to transmitter coil layers having only three coils.Instead, other embodiments can include transmitter coil layers havingmore than three transmitter coils. In such embodiments, the transmittercoils are arranged equally spaced apart and placed in positionscorresponding to corners of equilateral triangles.

B. Expanding Transmitter Coil Patterns

Like the base pattern, the rosette pattern (or any other pattern formedfrom the base pattern) can be expanded to form larger sets oftransmitter coils for different shapes and sizes of wireless chargingmats. FIGS. 6A-6C illustrate an expansion of a pattern of transmittercoils according to some embodiments of the present disclosure. FIG. 6Aillustrates an initial pattern 600, and FIGS. 6B and 6C each illustratethe initial pattern after it has been expanded by an incrementaltransmitter coil layer.

Initial pattern 600 in FIG. 6A is shown as a transmitter coilarrangement 600 arranged in a rosette pattern, though one skilled in theart understands that any initial pattern formed from the base patterncan be used as the initial pattern. Initial pattern 600 includes threetransmitter coil layers where a first layer includes transmitter coils602 a-c, a second layer includes transmitter coils 604 a-c, and a thirdlayer includes transmitter coil 606 a. The second layer can be disposedbetween the first and third layers.

The way in which a pattern of transmitter coils may be expanded can bebased on its existing transmitter coil arrangement. For instance, addinga transmitter coil to the existing pattern can be based on the layers inwhich the closest transistor coils are positioned, where the transmittercoil added to the pattern is placed in the layer in which the closesttransmitter coils are not positioned. As an example, if the closesttransmitter coils are positioned in the first and second layers, thenthe next transmitter coil used to expand the pattern is positioned inthe third layer. Likewise, if the closest transmitter coils arepositioned in the first and third layers, then the next transmitter coilis placed in the second layer; and if the closest transmitter coils arepositioned in the second and third layers, then the next transmittercoil is placed in the first layer. This approach may be used to expandthe pattern each time an additional coil is added to the existingtransmitter coil arrangement. Each transmitter coil added to the patternis positioned according to the base pattern discussed herein withrespect to FIG. 3.

In the particular example shown in FIG. 6B, transmitter coils 606 b and606 c are added to transmitter coil arrangement 600 to form transmittercoil arrangement 601. Using the approach discussed herein, transmittercoils 606 b and 606 c are placed in the transmitter coil arrangement 601according to the positions of the outermost transmitter coils. Since theoutermost transmitter coils 602 b, 602 c, and 604 b, are positioned inthe first and second layers, transmitter coils 606 b and 606 c can bepositioned in the third layer. Expanding the pattern by anothertransmitter coil layer follows the same approach. For instance, as shownin FIG. 6C, transmitter coil 602 d is added to transmitter coilarrangement 601 to form transmitter coil arrangement 603. Since theoutermost transmitter coils 606 b, 606 c, and 604 b are positioned inthe second and third layers, transmitter coil 602 d can be positioned inthe first layer.

Transmitter coil arrangement 600 can be expanded to any degree accordingto any design. For instance, transmitter coil arrangement 600 can beexpanded according to a 16-coil design. FIG. 6D illustrates exemplarytransmitter coil arrangement 605 formed of 16 coils, according to someembodiments of the present disclosure. As shown, the transmitter coilsin transmitter coil arrangement 605 can be organized in an overlappingarrangement such that different coils in the plurality of coils are ondifferent planes and are non-concentric with each other. Transmittercoil arrangement 605 can be similar to the coil arrangement oftransmitter coil arrangement 200 briefly discussed herein with respectto FIG. 2. Thus, each transmitter coil can be positioned to providebroad coverage across charging surface 102 of charging mat 100.

In some embodiments, transmitter coil arrangement 600 can be expandedfurther according to a different design. As an example, transmitter coilarrangement 600 can be expanded according to a 22-coil design. FIG. 6Eillustrates exemplary transmitter coil arrangement 607 formed of 22coils, according to some embodiments of the present disclosure. Asshown, six additional coils can be added to the 16-coil design accordingto the steps explained herein with respect to FIGS. 6A-6C. Addingadditional coils can alter the shape and coverage of charging surface102. Furthermore, adding additional coils can change the density ofmagnetic flux across charging surface 102. More coils may result in alarger charging surface 102 and a greater density of magnetic fluxacross charging surface 102 than a transmitter coil arrangement withless coils.

C. Coverage of Transmitter Coil Patterns

According to embodiments of the present disclosure, transmitter coilsarranged in patterns formed from the base pattern can generate magneticfields that form a continuous charging surface. The continuous chargingsurface allows electronic devices resting upon the charging surface toreceive power in any location within it, thereby enhancing the ease atwhich a user may charge his or her device.

FIGS. 7A-7C illustrate how the pattern of the transmitter coils createsthe continuous charging surface, according to embodiments of the presentdisclosure. Each figure illustrates a separate layer of a transmittercoil arrangement and shows a corresponding graph plotting the strengthof a magnetic field across a distance. The graph plots the strength ofone transmitter coil, but can be applied to all transmitter coils in thesame layer. Each graph has a Y-axis representing strength of themagnetic field (which may be expressed by the unit H representingamperes per meter) increasing upward, and an X-axis representinghorizontal distance across a charging surface increasing to the right.

FIG. 7A illustrates an array of transmitter coils 700 and a graph 708representing a strength-to-distance curve of a magnetic field generatedby a transmitter coil 702, according to some of the present disclosure.Array of transmitter coils 700 can be an array of transmitter coilspositioned within a first layer of a transmitter coil arrangement. Insome embodiments, transmitter coil 702 generates a magnetic field havinga strength-to-distance curve 714 that peaks near the center oftransmitter coil 702 and decreases as you move farther away from thecenter of curve 714.

In order for the transmitter coil to perform wireless charging, thetransmitter coil may need to generate a magnetic field that is strongenough to extend above a charging surface. The threshold at whichwireless charging is enabled may be represented by a strength threshold715 shown in graph 708. Portion of curve 714 above strength threshold715 may be sufficient for wireless charging, and those portions of curve714 below strength threshold 715 may be insufficient for wirelesscharging. Portions of curve 714 below strength threshold 715 may bedesignated as “dead zones” 716 and 718 where the magnetic field is notstrong enough to wirelessly charge an electronic device resting on thecharging surface.

Thus, according to embodiments, additional layers can be incorporated inthe transmitter coil arrangement to fill in the dead zones. As shown inFIG. 7B, a second transmitter coil layer can be placed on top of thefirst transmitter coil layer in a manner congruent to the arrangement ofthe base pattern discussed herein to fill in at least some of the deadzones of the first layer, thereby resulting in transmitter coilarrangement 701. The second transmitter coil layer can include atransmitter coil 704 that has a magnetic field strength-to-distancecurve 720. By including transmitter coil 704 in the second layer, themagnetic fields generated by transmitter coil 704 (and other transmittercoils in the second layer) can fill in dead zone 718 from the firstlayer. Thus, portions of the charging surface corresponding to thetransmitter coils in the second layer may be able to perform wirelesscharging.

As can be appreciated from chart 720, there may still be some dead zoneseven with the addition of the second layer. For instance, portions ofdead zone 716 may still exist, thereby causing some regions of thecharging surface to not be capable of performing wireless charging, andresulting in a discontinuous charging surface. Thus, according to someembodiments of the present disclosure, a third layer can be incorporatedto fill in the remaining dead zones.

FIG. 7C illustrates a third transmitter coil layer formed on top of thefirst and second transmitter coil layers to form transmitter coilarrangement 703. In some embodiments, the second transmitter coil layercan be positioned between the first and third transmitter coil layers.Third transmitter coil layer can include a transmitter coil 706 that hasa magnetic field strength-to-distance curve 722. By includingtransmitter coil 706 in the third layer, the magnetic fields generatedby transmitter coil 706 (and other transmitter coils in the secondlayer) can fill in dead zone 716 from the first and second layers.Accordingly, there may no longer be any dead zones within the chargingsurface, thereby creating a continuous charging surface within which anelectronic device can be wirelessly charged when resting in anylocation.

Although FIGS. 7A-7C illustrate a transmitter coil arrangement that hasonly three layers to create a continuous charging surface, embodimentsare not limited to such configurations. Other embodiments can have moreor less than three layers to form a continuous charging surface, withoutdeparting from the spirit and scope of the present disclosure.

D. Rotational Arrangement of Transmitter Coils

Arranging the transmitter coils so that they overlap one another indifferent layers increases the z-height (e.g., thicknesses) of thetransmitter coil arrangement when assembled as compared to an array ofsimilar coils arranged in a single layer. According to some embodimentsof the present disclosure, transmitter coils in a transmitter coilarrangement can be oriented in various radial directions to minimize thez-height of a transmitter coil arrangement as described in variousembodiments discussed below. A radial direction is the angle at which atransmitter coil is radially aligned with respect to a referencedirection, which may be any arbitrary angular direction such as truenorth. The radial direction of a transmitter coil may be defined by anangular difference between a reference location of the transmitter coiland the reference direction.

FIG. 8A illustrates exemplary reference locations for transmitter coils801 a-b with respect to an exemplary reference direction 807. Exemplaryreference direction 807 may be an angular direction corresponding totrue north as shown in FIG. 8A. A reference location may be representedby any structural part of a transmitter coil that is common in all othertransmitter coils. For instance, a reference location 803 a oftransmitter coil 801 a can be represented by a termination end 805 oftransmitter coil 801 a. Likewise, a reference location 803 b oftransmitter coil 801 b can be represented by a corresponding terminationend 805 b of transmitter coil 801 b. The radial direction of transmittercoil 801 a can be defined by the angle between reference location 807and reference location 803 a, and the radial direction of transmittercoil 801 b can be defined by the angle between reference direction 807and reference location and 803 b. Thus, transmitter coil 801 a may bearranged in a different radial direction than transmitter coil 801 b asshown in FIG. 8A.

The particular way these transmitter coils are arranged can be based onone or more factors. For instance, the structure of the transmitter coilcan include protrusions that can fit in the spaces between transmittercoils in adjacent layers, thereby minimizing z-height. As an example, atransmitter coil in the first layer can have protrusions that fit in thespace between adjacent transmitter coils in the second layer. Details ofsuch structures will be discussed further herein.

Transmitter coils in different transmitter coil layers can be arrangedin different radial directions. FIG. 8B illustrates an exemplarytransmitter coil arrangement 800 formed of three transmitter coillayers: a first transmitter coil layer 802, a second transmitter coillayer 804, and a third transmitter coil layer 806, where the transmittercoils of each layer is arranged in a different radial direction than theother layers. Transmitter coil arrangement 800 is shown in anarrangement suitable for a pill-shaped wireless charging mat, such aswireless charging mat 100 in FIGS. 1 and 2, though it is to beappreciated that embodiments are not limited to such arrangements, andthat other embodiments can have transmitter coil arrangements suitablefor other shapes of wireless charging mats without departing from thespirit and scope of the present disclosure.

As shown in FIG. 8B, transmitter coils of first transmitter coil layer802 can be arranged in a first radial direction 808, transmitter coilsof second transmitter coil layer 804 can be arranged in a second radialdirection 810, and transmitter coils of third transmitter coil layer 806can be arranged in a third radial direction 812. First, second, andthird radial directions 808, 810, and 812 can be offset from one anotherby an angular offset 814. The degree angular offset 814 may bedetermined to be an angle that enables transmitter coils of first,second, and third transmitter coil layers 802, 804, and 806 to achieveminimal z-height when transmitter coil arrangement 800 is assembled, aswill be discussed in detail further herein. In some embodiments, angularoffset 814 ranges between 110 to 130 degrees, particularly around 120degrees in certain embodiments.

While transmitter coils in different layers can be arranged in differentradial directions, transmitter coils in the same coplanar layer can bearranged in the same radial direction. To better illustrate thisconcept, FIGS. 9A-9C each illustrate a different transmitter coil layerof transmitter coil arrangement 800 in FIG. 8B. Specifically, FIG. 9Aillustrates first transmitter coil layer 802, FIG. 9B illustrates secondtransmitter coil layer 804, and FIG. 9C illustrates third transmittercoil layer 806.

As can be seen from FIGS. 9A-9C, transmitter coils 802 are all arrangedin the same radial direction, e.g., first radial direction 808.Likewise, transmitter coils 804 are all arranged in radial direction810, and transmitter coils 806 are all arranged in radial direction 812.In some embodiments, the transmitter coils in the same layer aresubstantially coplanar. Additionally, adjacent transmitter coils in thesame coplanar layer are positioned the same distance away from oneanother, as discussed herein with respect to FIGS. 5A and 5B.Furthermore, each set of transmitter coils in a coplanar layer aresymmetrical across a horizontal axis 900. In some embodiments, only twoout of the three layers of transmitter coils has the same number oftransmitter coils. For instance, transmitter coils 802 in the firstlayer has the same number of transmitter coils as transmitter coils 804in the second layer. Transmitter coils 806 in the third layer can have adifferent number of transmitter coils than the other two layers, such astwo less transmitter coils than the other two layers. This phenomenon isan artifact of the expanded rosette pattern discussed herein above.

FIGS. 8B and 9A-9C illustrate one exemplary transmitter coilarrangement; however, embodiments are not limited to such arrangements.Other embodiments can have different transmitter coil arrangements. Asan example, FIG. 10 illustrates an exemplary transmitter coilarrangement 1000 that includes sixteen individual coils where thetransmitter coils are arranged in different radial directions based ontheir position in the transmitter coil arrangement, according to someembodiments of the present disclosure. For instance, transmitter coilarrangement 1000 can include twelve outer transmitter coils 1002 andfour inner transmitter coils 1004. Outer transmitter coils 1002 may be aset of transmitter coils positioned near the outermost regions oftransmitter coil arrangement 1000, while inner transmitter coils 1004may be those transmitter coils surrounded by outer transmitter coils1002. As shown in FIG. 10, inner transmitter coils 1004 are indicated bybolded lines, and outer transmitter coils 1002 are indicated bynon-bolded lines for ease of observation.

In some embodiments, outer transmitter coils 1002 are arranged in adifferent radial direction than inner transmitter coils 1004. As shownin FIG. 10, outer transmitter coils 1002 can be arranged in a radialdirection pointing toward the outer edges of transmitter coilarrangement 1000, while inner transmitter coils 1004 can be arranged invarious radial directions. Arranging outer transmitter coils 1002 insuch a manner enables some portions of outer transmitter coils 1002 tobe positioned away from an inner region of a charging surface. Suchportions may be less efficient portions of the transmitter coils due tothe structural configuration of the transmitter coil, as will bediscussed further herein.

Given the multi-layered construction of transmitter coil arrangement1000, transmitter coils in the same coplanar layer can be arranged indifferent directions. FIGS. 11A-11C each illustrate a differenttransmitter coil layer of transmitter coil arrangement 1000 in FIG. 10.Specifically, FIG. 11A illustrates a first transmitter coil layer 1102,FIG. 11B illustrates a second transmitter coil layer 1104, and FIG. 11Cillustrates a third transmitter coil layer 1106 of transmitter coilarrangement 1000.

As can be seen from FIGS. 11A-11C, one or more transmitter coils infirst transmitter coil layer 1102 are arranged in a different radialdirection than other transmitter coils in the same layer. Transmittercoils that are part of outer transmitter coils 1002 in FIG. 10, e.g.,transmitter coils 1108 a, 1108 b, 1108 d, 1108 e, and 1108 f, can bearranged so that their radial direction face outward as discussed hereinwith respect to FIG. 10 to achieve a more even charging surface across awireless charging mat. Conversely, transmitter coils that are part ofinner transmitter coils 1104 in FIG. 10, e.g., transmitter coil 1108 c,can be arranged so that its radial direction is an increment of between110 to 130 degrees, such as 120 degrees discussed herein with respect toFIG. 8B. Transmitter coils that are part of respective inner and outertransmitter coils in the second and third transmitter coil layers, asshown in FIGS. 11B and 11C, can also be arranged based on the sameprinciples.

Transmitter coils shown in FIGS. 2-11C in respective transmitter coilarrangements can have similar dimensions. For example, transmitter coilsin each transmitter coil arrangement can have the same inner diameterand outer diameter. FIG. 12A illustrates an exemplary transmitter coilarrangement 1200 where all of the transmitter coils have substantiallythe same dimensions, e.g., the same inner and outer diameters. An innerdiameter can be defined by the diameter of a perimeter formed by theturn of a transmitter coil that is closest to its center, and an outerdiameter can be defined by the diameter of a perimeter formed by theturn of a transmitter coil that is farthest from its center. Forinstance, transmitter coil 1202 a can have an inner diameter 1204 and anouter diameter 1206. Even transmitter coils 1202 b and 1202 c positionedat the farthest left and right positions in transmitter coil arrangement1200 can have substantially the same dimensions as all other transmittercoils. In some embodiments, transmitter coils have substantially thesame dimensions when their respective inner and outer diameters differby less than 10%, particularly less than 5% in certain embodiments.

Although transmitter coils arrangement discussed herein can have thesubstantially the same dimensions, some embodiments can have transmittercoil arrangements where some transmitter coils have different dimensionsthan other transmitter coils in the same transmitter coil arrangement,as will be discussed herein with respect to FIG. 12B.

FIG. 12B illustrates an exemplary transmitter coil arrangement 1201where one or more transmitter coils have different dimensions than othertransmitter coils in transmitter coil arrangement 1201, according tosome embodiments of the present disclosure. In some embodiments, allother transmitter coils in transmitter coil arrangement 1200 can havethe same inner and outer diameters 1204 and 1206 except for thetransmitter coils that are positioned at the farthest left and rightpositions of transmitter coil arrangement 1200, such as transmittercoils 1202 b and 1202 c.

Transmitter coils 1202 b and 1202 c can have a smaller inner diameterthan all other transmitter coils in transmitter coil arrangement 1200because of their positions. The farthest left and right positions oftransmitter coil arrangement 1200 have the least density of transmittercoils by virtue of being at the very edge of the transmitter coilarrangement. Thus, magnetic flux generated in those positions may beless dense than magnetic flux generated at other areas of transmittercoil arrangement 1200, such as magnetic flux generated near the centerof transmitter coil arrangement 1200. Accordingly, one or moretransmitter coils located at the farthest left and right positions canhave different coil dimensions to increase the magnetic flux densityproduced at those areas of the transmitter coil arrangement. Forinstance, transmitter coils 1202 b and 1202 c can have a smaller innerdiameter 1208 but the same outer diameter 1210 when compared to othertransmitter coils in transmitter coil arrangement 1200, e.g.,transmitter coil 1202 a. By having a smaller inner diameter, transmittercoils 1202 b and 1202 c can have more turns, thereby being capable ofgenerating a greater amount of flux. In some embodiments, inner diameter1208 is approximately three to five mm less than inner diameter 1204.For instance, inner diameter 1208 can be approximately 4 mm less thaninner diameter 1204 such that inner diameter 1208 is 13 mm and innerdiameter 1204 is 17 mm. It is to be appreciated that other embodimentscan modify the shape and/or geometry of the transmitter coils to achievea smoother charging region. Additionally, the shape of one or moretransmitter coils can be modified based on the geometry of the wirelesscharging mat and the location of the transmitter coils with respect tothe wireless charging mat. For instance, if the wireless charging mat isin the general shape of a square or of another shape that has severalstraight edges, some transmitter coils disposed at the edges of thewireless charging mat can be in the shape of a “D” such that thestraight edges of the transmitter coil can correspond to the straightedges of the wireless charging mat.

III. Transmitter Coil Structure

As illustrated in FIGS. 2-12, the transmitter coils are shown ascircular “O”-shaped rings. It is to be appreciated that the circular“O”-shaped rings represent a coil of wire for generating time-varyingmagnetic fields capable of inducing a corresponding current in areceiver coil for performing wireless charging. In some embodiments, thecoil of wire may be formed of a coil of wire where each turn of the wireincludes a bundle of smaller coils of wire. In other embodiments, thecoil of wire may be formed of a coil of wire where each turn of the wireincludes a single core of conductive material. While FIGS. 2-12illustrate the transmitter coils as circular rings, in some embodimentseach transmitter coil can an outer perimeter with a generally circularshape that is not a perfect circle due to the width of the wire and thespiraling nature of the wire as described in further detail below. Asused herein, a “generally circular” coil refers to both a coil with acircular perimeter and a coil that has a perimeter that is close tobeing circular as discussed below. In other embodiments, transmittercoils may be non-circular, such as hexagonal so that the coils maymaximize usage of the space between adjacent transmitter coils, or anyother suitable shape, e.g., square, oval, rectangular, triangular, andthe like.

A. Transmitter Coil Wiring

FIG. 13A illustrates an exemplary coil of wire 1300 formed of aplurality of thin wires, according to some embodiments of the presentdisclosure. A single turn of wire can include a bundle 1302 of smallconductive wires, as shown in FIG. 13B. FIG. 13B illustrates across-sectional view 1301 of a single turn of wire of coil 1300. Thesingle turn of wire can include multiple thin wires 1305, which can bearranged in sub-bundles, such as sub-bundles 1303 a, 1303 b, and 1303 c.The overall width of bundle 1302 of wires may be determined by thethickness of each thin wire 1305 and the manner in which the bundle 1302of thin wires are arranged (e.g., how many thin wires 1305 are stackedtogether in the z direction to define the height, H, of eachsub-bundle). In some embodiments, the thickness of each thin wire 1305may range between 110 and 120 microns, resulting in a bundle 1302 ofthin wire having a width ranging between 1 to 2 mm and a height (H)ranging between 0.4 to 0.7 mm. Using a bundle of thin wire for each turnof the coil may be particularly useful for generating stronger magneticfields given its ability to achieve a large number of turns in a limitedamount of space.

Coil of wire 1300 may be formed of a coil of wire that winds between aninner radius 1304 to an outer radius 1306. In some embodiments, coil ofwire 1300 can be a flattened “0”-ring formed of single layer of wirethat winds from inner radius 1304 to the outer radius 1306, or viceversa. Inner radius 1304 can be a non-zero radius that allows coil ofwire 1300 to have a vacant inner space. Having the coil of wire 1300wind in a single layer of wire minimizes the overall height of the coil,which thereby decreases the overall height of the wireless charging matonce the coils are assembled.

In particular embodiments, each thin wire 1305 is an electricallyinsulated wire that is covered in one or more layers of dielectricmaterial, such as polyurethane. The layer of electrical insulationprevents the thin wires from shorting with an adjacent thin wire whencoiled. Additionally, coil of wire 1300 as a whole can be covered withanother layer of insulating material, such as polyimide, to attach thewound wires together to form a single structure of coiled wire. Coil ofwire 1300 can be attached to a bobbin, as will be discussed furtherherein, and can thus be easily picked up and placed (e.g., using a robotas part of a manufacturing process) in a transmitter coil arrangement.

In some embodiments, instead of using a bundle of smaller coils, asingle core of conductive material may be used for each turn of wire, asshown in FIG. 13C. FIG. 13C illustrates an exemplary coil of wire 1307formed of a single core of conductive wire, according to someembodiments of the present disclosure. FIG. 13D illustrates across-sectional view 1309 of a single turn of wire of coil 1307. Asshown in cross-sectional view 1309, the single turn of wire may beformed of a single core of conductive wire 1311 instead of a bundle ofwires 1302 as shown in FIG. 13B. Using a single core of conductive wirefor each turn of the coil of wire may be particularly useful forapplications where the transmitter coil is formed in a PCB, which can beprinted with conductive lines having very small dimensions. In someembodiments, the single core of conductive wire can have a width between0.9 and 1.3 mm, and a height between 0.08 to 0.18 mm.

With reference back to FIG. 13A, coil of wire 1300 can have twotermination ends: first termination end 1308 and second termination end1310. The termination ends may be the avenue through which current canenter and exit through coil of wire 1300. In some embodiments,termination end 1310 can fold over coil 1300 to be positioned within aninner diameter of coil 1300 as shown in FIGS. 14A and 14B.

Specifically, FIG. 14A illustrates a top perspective view of a coil ofwire 1400 with termination ends 1402 and 1404 positioned within aninternal diameter 1406 of coil of wire 1400, according to someembodiments of the present disclosure, and FIG. 14B illustrates a sideview of coil of wire 1400. Positioning termination ends 1402 and 1404within the internal diameter of coil of wire 1400 simplifies how coil1400 is coupled to another structure, such as a driver board, because itenables the coupling to be performed at a single location, e.g., thecenter of coil of wire 1400.

As shown in FIG. 14A, termination end 1402 bends over coil 1400 so thatit is positioned within internal diameter 1406. Although termination end1402 appears to bend over coil 1400 without folding over on itself,embodiments are not limited to such arrangements and that embodimentswhere termination end 1402 folds over itself to be positioned withininternal diameter 1406 are envisioned herein as well. In someembodiments, a portion 1408 of the termination end 1402 rests on coil1400 so that it protrudes above a plane of coil 1400. For instance, withreference to FIG. 14B, portion 1408 can extend above a plane 1410 ofcoil 1400 as defined by a surface formed by the winding of wire of coil1400. The protrusion may be positioned on only one side of coil 1400 sothat the other side of coil 1400 may not have a protrusion. Unliketermination end 1402, termination end 1404 may not protrude above plane1410 as it may already be positioned within internal diameter 1406. Insome embodiments, termination end 1404 can merely bend toward the centerof coil 1400 without folding over coil 1400.

With reference back to FIG. 14A, the directions at which terminationends 1402 and 1404 turn toward the center of coil 1400 can, in someembodiments, form an angle 1412 with respect to each other. Angle 1412may be determined based on an offset angle, such as offset angle 814discussed herein with respect to FIG. 8B. Offset angle 814 may enablethe overlapping portion 1408 of coil 1400 to be positioned in a gapbetween transmitter coils in an adjacent layer to minimize the z-heightof a transmitter coil stack, as will be discussed further herein.

As can be appreciated from FIG. 14A, a portion of coil of wire 1400 canhave a different number of turns than other regions. For example, region1414 of coil 1400 can have four turns of wire, while the rest of coil1400 (e.g., regions of coil 1400 that is not part of region 1414) hasfive turns of wire as shown in FIG. 14A. In another example (not shownin FIG. 14A), region 1414 of coil 1400 can have more turns than the restof coil 1400. It is to be appreciated that having more or less turns inregion 1414 depends on the arrangement of termination ends 1402 and 1404which define where the winding begins and ends. Accordingly, region 1414may have different coupling characteristics with other transmitter coilswhen arranged in a transmitter coil arrangement than the other regionsof coil 1400. As an example, region 1414 may have more coupling withother transmitter coils in a transmitter coil arrangement. Having morecoupling may reduce the efficiency of the transmitter coil. Thus, insome embodiments, region 1414 may be minimized to mitigate coupling withother transmitter coils by reducing the angle at which termination ends1402 and 1404 are positioned. For example, termination ends 1402 and1404 can be positioned parallel to one another, as shown in FIG. 14C. Insome embodiments, region 1414 is less than half of coil 1400 such thatregion 1414 is a smaller portion of coil 1400 than the rest of coil1400.

FIG. 14C illustrates an exemplary coil of wire 1401 where terminationends 1402 and 1404 are arranged parallel to one another. By arrangingtermination ends 1402 and 1404 parallel to one another, region 1416 ofcoil 1401 having less turns than other regions of the coil may beminimized. For instance, region 1416 having only four turns of wire maybe minimized to be the small distance between termination ends 1402 and1404 shown in FIG. 14C. In comparison, region 1416 may be substantiallysmaller than region 1414 in FIG. 14A. Accordingly, by minimizing region1416, coil 1401 may operate in a more efficient manner.

In some embodiments, due to the width of each turn of the wire thatmakes up coils 1400 and 1401, each coil can have a generally circularshape (as defined by the outer perimeter of the coil) that is not a truecircle. That is, some regions of the outer perimeter of coils 1400 and1401 may deviate from the outer perimeter of a true circle. For example,the outer perimeter of a true circle 1418, represented by dashed anddotted lines, is superimposed over coil 1400 and 1401 in FIGS. 14A and14C. Portions of the outer perimeter of coils 1400 and 1401 having lessturns, e.g., portions 1414 and 1416, may deviate from the outerperimeter of a true circle 1418 by having a shorter radius. Thenon-circular shape of the transmitter coils can dictate the organizationof a transmitter coil arrangement to ensure an even charging efficiencyacross the entire surface of the charging region, as will be discussedfurther below.

As will be appreciated further herein, the different ways thetermination ends are arranged may affect the radial directions of thecoils as discussed herein with respect to FIGS. 8-11C. Details of thisrelationship will be discussed further herein with respect to FIGS.17A-19.

B. Bobbin

According to some embodiments of the present disclosure, each coil ofwire is wound around, and the termination ends of each coil are attachedto, a central, disc-shaped support structure known as a “bobbin.” Thestructure formed by combining the coil of wire and the bobbin issometimes referred to as “a transmitter coil” throughout the disclosure.The bobbin is a support structure that not only provides structuralintegrity for the coil of wire, but also provides a structure to whichthe termination ends can attach for coupling with a respective pair ofcontact pins. The contact pins can electrically couple the coil of wireto a driver board for operating the coil of wire as a transmitter coilfor wireless charging.

FIGS. 15A-15D illustrate an exemplary bobbin 1500 according to someembodiments of the present disclosure. Specifically, FIG. 15Aillustrates a top perspective view of bobbin 1500, FIG. 15B illustratesa side-view of bobbin 1500, and FIGS. 15C and 15D illustrate side-viewsof exemplary bobbins 1520 and 1522, respectively. Bobbins 1520 and 1522may have similar features as bobbin 1500, except that their contacthousings and pins may be arranged differently, as discussed below.

Bobbin 1500 may be a generally flat and circular structure in the shapeof a disc including substantially planar surfaces. For example, bobbin1500 can have a substantially planar top surface 1502 and asubstantially planar bottom surface 1504 as shown in FIG. 15B. Withreference back to FIG. 15A, bobbin 1500 includes a contact housing 1506positioned near the center of bobbin 1500. A pair of contact pins 1508a-b can reside within contact housing 1502 for coupling with arespective pair of termination ends of a coil of wire. Contact pins 1508a-b may be contacts in the form of cantilever beams (or any othersuitable form of contacts) that are configured to make contact with padson a control board, e.g., a driver board formed as a PCB, for operatinga coil of wire (not shown) wound around angular bobbin 1500.

In some embodiments, contact housing 1506 can protrude past a planarsurface of bobbin 1500. As an example, contact housing 1506 can protrudepast planar top surface 1502 as shown in FIG. 15B. In another example,contact housing 1506 can protrude past both top and bottom surfaces 1502and 1504, respectively, as shown in FIG. 15C, or can protrude pastbottom surface 1504 as shown in FIG. 15D. Contact housing 1506 protrudespast a plane of bobbin 1500 to provide additional vertical space fortermination ends of a coil of wire to couple with contact pins 1508 a-b.For instance, contact housing 1506 may provide enough space for thetermination ends to be soldered to bobbin 1500. The resulting solderedstructure may occupy more vertical space than the thickness of bobbin1500 defined by top and bottom surfaces 1502 and 1504.

Bobbin 1500 can also include a pair of contact pads 1512 a-b. Contactpads 1512 a-b can provide a surface upon which termination ends of acoil of wire can attach to electrically couple with contact pins 1508a-b. For instance, contact pads 1512 a-b may be substantially flatsurfaces that are electrically coupled to respective contact pins 1508a-b. Bobbin 1500 may further include a pair of channels 1510 a-b toallow termination ends to couple with contact pads 1512 a-b. In someembodiments, channels 1510 a-b extend from outer rim 1516 toward contacthousing 1506, i.e., toward the center of bobbin 1500. Channels 1510 a-bcan provide an avenue through which the termination ends traverse tomake contact with contact pads 1512 a-b. As shown in FIG. 15A, channels1510 a-b can be vacant regions in bobbin 1500 where termination ends canbe positioned without substantially affecting the overall thickness ofbobbin 1500.

Bobbin 1500 can further include one or more openings 1516 a and 1516 b.Each opening 1516 a and 1516 b can be a vacant space that extendsthrough bobbin 1500 so that apparatuses can pass through from one sideof bobbin 1500 to the other. In some embodiments, openings 1516 a and1516 b are features that can be used to grab bobbin 1500 and to pick upand accurately place bobbin 1500 in specific locations, such as in atransmitter coil arrangement. Additionally, openings 1516 a and 1516 bprovide avenues through which apparatuses may traverse to secure bobbin1500 in a transmitter coil arrangement after being pick up and placed inits intended location.

In some embodiments, bobbin 1500 can include attachment pads 1514 forattaching the coil of wire to bobbin 1500. Any suitable adhesive, suchas an epoxy adhesive, may secure bobbin 1500 to the coil of wire byfixing the coil of wire to attachment pads 1514. Although FIG. 15A showsthree attachment pads 1514 disposed on only one side of bobbin 1500,embodiments are not limited to such configurations. Other embodimentscan have more or less attachment pads and the attachment pads can bedisposed on either or both sides of the bobbin.

C. Angle Transmitter Coil

As shown in FIG. 15A, channels 1510 a-b of bobbin 1500 can be arrangedat an angle 1518 with respect to one another. Angle 1518 can be anon-zero angle that is particularly suitable for allowing transmittercoils to be arranged in a stack with minimal z-height. For instance,angle 1518 may be between 110 to 130 degrees, such as 120 degrees inparticular embodiments. Angle 1518 may correspond to angle 1412 betweenthe termination ends of coil 1400 in FIG. 14. As such, a coil of wirewound about outer rim 1516 of bobbin 1500 may result in the formation ofcoil 1400. According to some embodiments, winding a coil of wire aboutbobbin 1500 results in the formation of an angle transmitter coil asshown in FIGS. 16A and 16B.

FIGS. 16A and 16B illustrate top and bottom perspective views,respectively, of an exemplary angle transmitter coil 1600 formed of acoil of wire 1602 wound about bobbin 1604, according to some embodimentsof the present disclosure. As shown in FIG. 16A, termination ends 1606and 1608 can be attached to respective contact pads on bobbin 1604 at anangle, e.g., angle 1518 in FIG. 15A. Once attached to the contact pads,termination ends 1606 and 1608 can be electrically coupled to respectivecontact pins 1610 a-b in contact housing 1612. Thus, when contact pads1610 a-b are coupled to a driver board (not shown), the driver board canbe electrically coupled to coil 1602 to control the operation of angletransmitter coil 1600. Additionally, once coil of wire 1602 is woundabout bobbin 1604, angle transmitter coil 1600 is formed and constructedas a single structure that can be picked up and placed on a driver boardduring assembly of a wireless charging mat.

As can be seen from the bottom perspective view of angle transmittercoil 1600 in FIG. 16B, termination end 1608 can bend over coil 1602.Thus, in addition to contact housing 1612, termination end 1608 can alsoprotrude from a plane of angle transmitter coil 1600. In someembodiments, termination end 1608 and contact housing 1612 protrude fromthe same plane of angle transmitter coil 1600. This protrusion mayaffect the way the transmitter coils are radially oriented whenimplemented in a transmitter coil arrangement, as will be furtherdiscussed with respect to FIGS. 17A and 17B.

FIG. 17A illustrates an exemplary transmitter coil arrangement 1700formed with angle transmitter coils, according to some embodiments ofthe present disclosure. Each angle transmitter coil can be arranged in aradial direction suitable for minimizing the z-height of transmittercoil arrangement 1700 while also enabling contact pins from eachtransmitter coil to make contact with a driver board (not shown).Specifically, transmitter coil arrangement 1700 may be organized basedon the transmitter coil arrangement shown in FIGS. 8-9C. Similar to thediscussion herein with respect to FIGS. 8-9C, transmitter coils indifferent transmitter coil layers can be arranged in different radialdirections, e.g., radial directions 1704, 1706, and 1708 in the first,second, and third transmitter coil layers, to minimize the z-height oftransmitter coil arrangement 1700. Similar to radial directions 808,810, and 812 in FIG. 8B, radial directions 1704, 1706, and 1708 can bearranged in angular offsets of between 110 to 130 degrees, such as 120degrees. The angular offset is selected so that the termination endsthat protrude from a plane of the transmitter coil can be tucked betweenadjacent coils in another layer, thereby minimizing the z-height oftransmitter coil arrangement 1700.

FIG. 17B illustrates a zoomed-in, bottom perspective view of a portionof transmitter coil arrangement 1700. As shown, termination end 1710 ofan angle transmitter coil in a first transmitter coil layer can betucked in the space between adjacent transmitter coils 1712 and 1714 ina second transmitter coil layer. The space between adjacent transmittercoils may correspond to distance D1 discussed herein with respect toFIGS. 5A and 5B. Distance D1 may be larger than the width of atermination end, i.e., the width of a wire of a transmitter coil. Insome embodiments, distance D1 ranges between 1.5 to 2 mm.

Contact housings of transmitter coils are positioned in locations wherecontact pins can interface with the driver board without being blockedby another transmitter coil. For instance, the contact housings can bepositioned within central termination zones 1718 of the transmittercoils. Central termination zones 1718 may correspond to centraltermination zones 418 discussed herein with respect to FIG. 4.

D. Parallel Transmitter Coil

FIGS. 18A-18B illustrate an exemplary parallel transmitter coil 1800according to some embodiments of the present disclosure. Specifically,FIG. 18A illustrates a top perspective view of parallel transmitter coil1800, and FIG. 18B illustrates a bottom perspective view of paralleltransmitter coil 1800.

As shown in FIG. 18A, parallel transmitter coil 1800 can include a coilof wire 1802 wound about a bobbin 1804. Termination ends 1806 and 1808can be attached to respective contact pads on bobbin 1804 and arrangedparallel to one another. When termination ends 1806 and 1808 arearranged in parallel, a portion 1814 of coiled wire 1802 defined by theregion between termination ends 1806 and 1808 may be smaller thanportion 1614 of coiled wire 1602. Thus, parallel transmitter coil 1800may be more efficient than angle transmitter coil 1800. Once attached tothe contact pads, termination ends 1806 and 1808 may be electricallycoupled to respective contact pins 1810 a-b in contact housing 1812.Thus, when contact pads 1810 a-b are coupled to a driver board (notshown), the driver board may be electrically coupled to coil 1802 tocontrol the operation of angle transmitter coil 1800.

As can be seen from the bottom perspective view of parallel transmittercoil 1800 in FIG. 18B, contact housing 1812 can protrude from a plane ofparallel transmitter coil 1800. Termination end 1808 can bend over coil1802 and also protrude from a plane of parallel transmitter coil 1800.In some embodiments, termination end 1808 and contact housing 1812protrude from the same plane of angle transmitter coil 1800. Thisprotrusion may affect the way the transmitter coils are radiallyoriented when implemented in a transmitter coil arrangement.

FIG. 19 illustrates an exemplary transmitter coil arrangement 1900formed with parallel and angle transmitter coils, according to someembodiments of the present disclosure. Each transmitter coil can bearranged in a radial direction suitable for maximizing efficiency of aninterior region of transmitter coil arrangement 1900 while alsominimizing z-height and enabling contact pins from each transmitter coilto make contact with a driver board (not shown). Specifically, thetransmitter coil stack can be arranged according to the transmitter coilarrangement shown in FIGS. 10-11C. Transmitter coil arrangement 1900 maysimilarly include outer transmitter coils 1902 and inner transmittercoils 1904. Outer transmitter coils 1902 may be a single line oftransmitter coils positioned near the outermost regions of transmittercoil arrangement 1900, while inner transmitter coils 1904 may be thosetransmitter coils surrounded by outer transmitter coils 1902.

In some embodiments, outer transmitter coils 1902 may be paralleltransmitter coils arranged in radial directions pointing toward theouter edges of transmitter coil arrangement 1900, e.g., the outerperimeter of the wireless charging mat within which transmitter coilarrangement 1900 is disposed. For instance, portions 1906 of outertransmitter coils 1902 that have less turns of wire, e.g., the lessefficient portions of the coil of wire such as portion 1814 in FIG. 18A,can be oriented toward the outer edges of transmitter coil arrangement1900. Accordingly, the rest of the portions of outer transmitter coils1904 having more turns and better efficiency may be concentrated towardthe interior of transmitter coil arrangement 1900. This helps ensurethat the wireless charging mat has a more consistent and efficientcharging surface in the inner regions of the charging surface.

While outer transmitter coils 1902 may be formed of parallel transmittercoils, inner transmitter coils 1904 may be formed of angle transmittercoils because of the spatial constraints caused by the arrangement ofouter transmitter coils 1902. To fit inner transmitter coils 1904 withintransmitter coil arrangement 1900 while minimizing z-height, innertransmitter coils 1904 may be arranged in various radial directionsaccording to the principles discussed herein with respect to FIG. 17A.That is, inner transmitter coils 1904 may be arranged in differentradial directions according to an angular offset of between 110 to 130degrees, such as 120 degrees, so that the termination ends that protrudefrom a plane of the angular transmitter coil can be tucked betweenadjacent coils in another layer, thereby minimizing the z-height oftransmitter coil stack 1900.

IV. Multi-Layer Arrangement of Transmitter Coils

To minimize the z-height of a transmitter coil arrangement, protrusionsof transmitter coils caused by contact housings and the folding-over oftermination ends of coils of wire may nest within the transmitter coilarrangement such that they do not protrude above or below thetransmitter coil arrangement as a whole. To better understand thisconcept, FIGS. 20A and 20B illustrate side-views of an exemplarytransmitter coil arrangement 2000 showing how the protrusion arepositioned when assembled. The nesting of transmitter coil arrangement2000 may be similar to, and a suitable representation of, how othertransmitter coil arrangements are nested, such as transmitter coilarrangements 800, 1000, 1700, and 1900 illustrated in FIGS. 8, 10, 17A,and 19.

FIG. 20A illustrates an exploded view of transmitter coil arrangement2000 to show how the protrusions are positioned. Transmitter coilarrangement 2000 can include a first transmitter coil 2002 in a firsttransmitter coil layer, a second transmitter coil 2004 in a secondtransmitter coil layer, and a third transmitter coil 2006 in a thirdtransmitter coil layer. Each transmitter coil may be representative ofother transmitter coils in the same layer. In some embodiments, firsttransmitter coil 2002 is positioned apart from third transmitter coil2006 while second transmitter coil 2004 is positioned between first andthird transmitter coils 2002 and 2006, respectively.

First transmitter coil 2002 can have a protrusion 2008 extending past aplanar surface 2010 of first transmitter coil 2002. Surface 2010 caninclude corresponding planar surfaces of both the coil of wound wire andportions of the bobbin around which the coil of wire is wound.Accordingly, in some embodiments, the planar surfaces of the coil ofwound wire and portions of the bobbin on corresponding sides of firsttransmitter coil 2002 may be substantially coplanar. Because otherportions of the bobbin may not substantially protrude above surface2010, the other portions are not shown as they are hidden behind thecoil of wire as perceived from the side-view perspective of FIG. 20A. Insome embodiments, protrusion 2008 can include the contact housing aswell as the folded-over termination end of the coil of wire. Contactpins 2026 of first transmitter coil 2002 can be positioned to extendpast a planar surface 2011 along a direction opposite of the protrusion.Contact pins 2026 protrude past planar surface 2011 to make contact withan underlying driver board, as will be discussed further herein.

Similar to first transmitter coil 2002, third transmitter coil 2006 canhave a protrusion 2012 extending past a planar surface 2014 of thirdtransmitter coil 2002. Protrusion 2012 can include a contact housing ofa bobbin and a folded-over termination end of a coil of wire woundaround the bobbin of third transmitter coil 2006. Contact pins 2024 ofthird transmitter coil 2006 can be positioned to extend past an end ofprotrusion 2012 (e.g., past the contact housing of the bobbin) along adirection with the protrusion. Contact pins 2024 extends past an end ofprotrusion 2012 to make contact with the underlying driver board.

As further shown in FIG. 20A, second transmitter coil 2004 can have aprotrusion that includes two portions: a first portion 2016 a and asecond portion 2016 b. First and second portions 2016 a and 2016 b caninclude a contact housing of a bobbin and a folded-over termination endof a coil of wire wound around the bobbin of second transmitter coil2004. First portion 2016 a can extend past a surface 2018 of secondtransmitter coil 2004, and second portion 2016 b can extend past asurface 2020 opposite of surface 2018. Contact pins 2022 of secondtransmitter coil 2004 can be positioned to extend past an end of secondportion 2016 b along a direction with second portion 2016 b to makecontact with the underlying driver board.

According to some embodiments of the present disclosure, protrusions2008 and 2012 of first and third transmitter coils 2002 and 2006,respectively, can be positioned toward second transmitter coil 2004 sothat when the transmitter coils are assembled into transmitter coilarrangement 2000, the protrusions do not protrude above or belowtransmitter coil arrangement 2000 as a whole. Additionally, the positionof the contact pads of the transmitter coils are arranged such that whenthe transmitter coils are assembled into transmitter coil arrangement2000, the contact pins can extend past a bottom surface of transmittercoil arrangement 2000 to make contact with an underlying driver board.The distance at which contact pins are positioned away from respectivesurfaces of the transmitter coils is configured such that they can makecontact with the driver board even after being assembled as transmittercoil arrangement 2000, as shown in FIG. 20B.

FIG. 20B illustrates assembled transmitter coil arrangement 2000attached to an underlying driver board 2028. When assembled, theprotrusions from the transmitter coils can be nested within transmittercoil arrangement 2000 as shown by the dotted lines representingprotrusions 2008, 2012, and 2016 a-b. In some embodiments, noprotrusions in transmitter coil arrangement 2000 extend above a topplane 2032 (i.e., surface 2013 of third transmitter coil 2006) or extendbelow a bottom plane 2030 (i.e., surface 2011 of first transmitter coil2002) of transmitter coil arrangement 2000. Accordingly, protrusion 2008can extend a distance from surface 2010 that is less than the combinedthickness of the coil of windings of second and third transmitter coils2004 and 2006; likewise, protrusion 2012 can extend a distance fromsurface 2014 that is less than the combined thickness of the coil ofwindings of first and second transmitter coils 2002 and 2004. Becausesecond transmitter coil 2004 is positioned between first and thirdtransmitter coils 2002 and 2006, portion 2016 a can extend a distancefrom surface 2018 that is less than the thickness of the coil ofwindings of third transmitter coil 2006, and portion 2016 b can extend adistance from surface 2020 that is less than the thickness of the coilof windings of first transmitter coil 2002.

In some embodiments, contact pins may be arranged to make contact withdriver board 2028 when transmitter coil arrangement 2000 is assembled.Thus, those transmitter coils that are positioned farthest away fromdriver board 2028 in the transmitter coil arrangement can have theircontact pins positioned farthest away from its coil of wire. Forinstance, as shown in FIG. 20B, third transmitter coil 2006 can bepositioned farthest away from driver board 2028. Thus, contact pins 2024can be positioned farthest away from the coil of wire of thirdtransmitter coil 2006 so that they can make contact with driver board2028 when transmitter coil arrangement 2000 is assembled. In someembodiments, as shown in FIG. 20A, contact pins 2024 are positioned adistance 2028 from surface 2014 of third transmitter coil 2006, contactpins 2022 are positioned a distance 2030 from surface 2020 of secondtransmitter coil 2004, and contact pins 2026 are positioned a distance2032 from surface 2011 of first transmitter coil 2002. Accordingly,distance 2028 may be greater than distance 2030 and 2032, distance 2030may be less than distance 2028 but greater than distance 2032, anddistance 2032 may be less than distances 2028 and 2030. By arranging thecontact pins of respective transmitter coils according to thesedistances, the contact pins can be positioned to make contact withunderlying driver board 2028, as shown in FIG. 20B, even though thecoils with which they are coupled are positioned at different distancesaway from driver board 2028.

It is to be appreciated that contact pins 2022, 2024, and 2026 extendtoward driver board 2028 regardless of which direction protrusions 2016a-b, 2012, and 2008 extend. As an example, contact pins 2026 of firsttransmitter coil 2002 extend downward toward driver board 2028 eventhough its protrusion 2008 extends upward. Contact pins 2022, 2024, and2026 extend toward driver board 2028 to make contact with driver board2028 so that control board 2028 can operate the transmitter coils toperform wireless charging.

V. Transmitter Coils without Bobbins

Aforementioned embodiments discussed herein are directed to transmittercoil arrangements formed of transmitter coils with bobbins. However, itis to be appreciated that transmitter coil arrangements according toembodiments of the present disclosure are not required to be formed oftransmitter coils with bobbins. In some embodiments, the transmittercoil arrangements may be formed of transmitter coils without bobbins andyet still achieve the same coverage, performance, and efficiency oftransmitter coil arrangements formed of transmitter coils with bobbins.

FIG. 21 illustrates an exemplary transmitter coil 2100 without a bobbin,according to some embodiments of the present disclosure. Transmittercoil 2100 can include a coil of wire 2102 wound between an inner radius2104 and an outer radius 2106. Coil of wire 2102 can be formed of aplurality of thin wires, similar to coil of wire 1200 in FIG. 12A, orformed of a single core of conductive material, similar to coil of wire1300 in FIG. 13A.

In some embodiments, coil of wire 2102 may wind from an initial location2108 to a termination location 2110. Initial location 2108 may be aposition along coil of wire 2102 where the wire initiates winding, andtermination location 2110 may be a position along coil of wire 2102where the wire terminates winding. The windings of wire may notsubstantially diverge from one another between initial location 2108 andtermination location 2110. In some embodiments, termination location2108 can be positioned based on initial location 2108 to achieve asubstantially even winding profile. For instance, termination location2108 can be positioned directly across coil of winding 2102 from initiallocation 2108. By positioning initial location 2108 and terminationlocation 2110 this way, the number of windings may be as close to awhole integer as possible, thereby achieving a substantially evenwinding profile. The substantially even winding profile can minimize thesize of a portion 2116 that has a different number of turns than therest of transmitter coil 2100, as discussed herein with respect to FIGS.14A and 14C. Furthermore, the number of turns may be determinedaccording to a target inductance value determined by design. As moreturns are formed in a transmitter coil, the inductance of thetransmitter coil increases. Having too much inductance in a transmittercoil may create inefficient power delivery. In particular embodiments,the number of turns may range between six to eight turns, such as seventurns in some embodiments.

Transmitter coil 2100 can also include a first termination end 2112 anda second termination end 2114. Each termination end 2122 and 2214 can bea point at which coil of wire 2102 physically ends. Unlike transmittercoils with bobbins, second termination end 2114 may not fold over coilof wire 2102 to be positioned within the inner diameter of transmittercoil 2100. Instead, second termination end 2114 may begin to divergeaway from coil of wire 2102 at termination location 2110 and stopoutside of coil of wire 2102. First and second termination ends 2112 and2114 can couple with first and second termination zones 2118 and 2120 tomake contact with an underlying driver board. First termination zone2118 may be positioned within the inner diameter of transmitter coil2100, but second termination zone 2120 may be positioned outside of theinner diameter of transmitter coil 2100. In some embodiments, secondtermination zone 2120 may be positioned within another transmitter coilwhen transmitter coil 2100 is assembled in a transmitter coilarrangement, as discussed herein with respect to FIG. 22.

FIG. 22A illustrates an exemplary transmitter coil arrangement 2200formed of transmitter coils without bobbins, according to someembodiments of the present disclosure. Positions of the transmittercoils in transmitter coil arrangement 2200 can be controlled by carriersthat define the positions of the transmitter coils according to therespective positions shown in FIG. 22A during assembly. Each carrier caninclude an array of bosses that define the location of the transmittercoils. The bosses can protrude from the carrier surface and provide astructure around which the transmitter coils may be positioned. In someembodiments, each carrier temporarily holds the transmitter coils inplace until they are secured to contacts on a driver board. Each carriermay be specific to a different layer of the transmitter coilarrangement. Once the transmitter coils are secured to the driver board,the carrier may be removed, thereby leaving the transmitter coils intheir respective positions according to the transmitter coilarrangement. Each layer is assembled, one-by-one, until all the layersare assembled to form the transmitter coil arrangement shown in FIG. 22.As will be discussed further herein, each layer of transmitter coils intransmitter coil arrangement 2200 can be fixed in position by a cowling.

Each transmitter coil can be arranged in a radial direction suitable forminimizing coupling within an interior region of transmitter coilarrangement 2200, while also enabling termination ends of eachtransmitter coil to make contact with a driver board (not shown).Similar to transmitter coil arrangement 1900 in FIG. 19, transmittercoil arrangement 2200 can be arranged in three transmitter coil layersaccording to the transmitter coil arrangement shown in FIGS. 10-11C.Thus, transmitter coil arrangement 2200 can include outer transmittercoils 2202 and inner transmitter coils 2204. Outer transmitter coils2202 may be a single line of transmitter coils positioned near theoutermost regions of transmitter coil arrangement 2200, while innertransmitter coils 2204 may be those transmitter coils surrounded byouter transmitter coils 2202.

In some embodiments, outer transmitter coils 2202 may be arranged in afirst radial arrangement where its radial directions point toward theouter edges of transmitter coil arrangement 2200 so that their regionsthat have a different number of turns, e.g., region 2116 in FIG. 21, areoriented toward the outer edges of transmitter coil arrangement 2200.Thus, the portions of outer transmitter coils 2204 having more turns andlower coupling tendencies may be concentrated toward the interior oftransmitter coil arrangement 2200. This helps ensure that the wirelesscharging mat has a more consistent and efficient charging surface in theinner regions of the charging surface. Additionally, inner transmittercoils 2204 may be arranged in a second radial arrangement different thanthe first radial arrangement. The second radial arrangement can be whereinner transmitter coils 2204 are arranged according to different angularoffsets with respect to one another as shown in FIG. 22. For instance,inner transmitter coils 2204 can be arranged in angular offsets between50-70 degrees, particularly 60 degrees in some embodiments. Arranginginner transmitter coils 2204 according to the second radial arrangementallows their termination ends to reach an underlying interconnectionstructure by terminating in the inner diameters of adjacent transmittercoils.

Given that transmitter coils without bobbins do not have a folding-overportion nor a bobbin that protrudes from a plane of a winding of coil,inner transmitter coils 2204 do not need to be arranged in a radialdirection that nests the protrusions in adjacent layers to minimizez-height. Instead, inner transmitter coils 2204 may only need to bearranged so that their second termination ends can make contact with anunderlying driver board (not shown). The second termination ends of thetransmitter coils can make contact with the underlying driver board whenthe second termination zones are positioned so that they are not blockedby another transmitter coil. Accordingly, the second termination zonesfor the inner transmitter coils 2204 can be positioned within an innerdiameter of an adjacent transmitter coil. As shown in FIG. 22, innertransmitter coils 2204 can be arranged in various radial directionsoffset from one another at an angular offset of between 50 and 70degrees, such as approximately 60 degrees in some embodiments. Arranginginner transmitter coils 2204 in this way allows their second terminationzones to be positioned within the inner diameter of neighboringtransmitter coils so that their second termination ends can make contactwith the underlying driver board.

As can be seen in FIG. 22A, each transmitter coil can have an outertermination zone 2208 and an inner termination zone 2206 whererespective termination ends reside. As mentioned herein, eachtermination zone may be a region where a termination end is positioned.The termination end can be a point at which a winding of the respectivetransmitter coil physically ends, but whose electrical connection cancontinue if it is coupled with a standoff for connecting with anunderlying driver board. Outer termination zone 2208 can be atermination zone that is positioned outside of an outer diameter of itsrespective transmitter coil, e.g., transmitter coil 2210. Innertermination zone 2208 can be a termination zone that is positionedinside an inner diameter of its respective transmitter coil. Thus, outertransmitter coils can have an outer termination zone that is positionednear an outer perimeter of the transmitter coil arrangement, and innertransmitter coils can have outer termination zones that are positionedwithin an inner diameter of an adjacent transmitter coil. For instance,transmitter coil 2212 can be positioned as an inner transmitter coil andhave an outer termination zone 2214 that is positioned in an innerdiameter of adjacent transmitter coil 2218.

Given that each transmitter coil has two termination zones, it can beappreciated that a transmitter coil arrangement can have numeroustermination zones for coupling with an underlying driver board. In manycases, the positions of these termination zones can affect theefficiency at which the transmitter coil arrangement operates. Thus, insome embodiments, termination zones of a transmitter coil arrangementcan be arranged to have a degree of similarity to improve simplicity indesign and improvement in operating efficiency, as discussed herein withrespect to FIGS. 22B-22E.

FIG. 22B is a simplified diagram illustrating an exemplary transmittercoil arrangement 2201 formed of transmitter coils without bobbins andwith similarly organized termination ends, according to some embodimentsof the present disclosure. Transmitter coil arrangement 2201 is formedof 22 transmitter coils arranged in an overlapping arrangement such thatdifferent coils in the plurality of coils are on different planes andeach transmitter coil of the transmitter coil arrangement has a centralaxis that is positioned a lateral distance away from central axes of allother transmitter coils, as discussed herein with respect to FIGS. 3-7C.According to some embodiments of the present disclosure, theorganization of termination zones can be derived according to a basepattern of termination zones that is repeated substantially throughoutthe transmitter coil arrangement. As an example, transmitter coilarrangement 2201 can have termination zones that are substantiallypositioned according to a base pattern 2220. In some embodiments, basepattern 2220 is established by the termination zones of five transmittercoils shown with bolded lines in FIG. 22B. The termination zones of basepattern 2220 can be repeated throughout a majority of transmitter coilarrangement 2201 except for the termination zones of the farthest leftand right transmitter coils. The termination zones of those farthestleft and right transmitter coils can be positioned such that onetermination zone is outside of the coil and the other termination zoneis inside of the coil.

A more detailed view of the transmitter coils in transmitter coilarrangement 2201 can be seen in FIGS. 22C-E. FIGS. 22C-E are simplifieddiagrams of sets of transmitter coils in each layer of transmitter coilarrangement 2201. FIG. 22C illustrates the angular orientations of afirst set of transmitter coils 2222. As shown in FIG. 22C, transmittercoils 2228 b, 2228 c, 2228 e and 2228 f that are positioned amongst theouter transmitter coils can have angular orientations that are eithervertically upward or downward, except for the farthest right transmittercoil 2228 g when arranged in transmitter coil arrangement 2201.Transmitter coils 2228 a and 2228 d that are positioned amongst theinner transmitter coils can have angular orientations that arevertically upward. As shown in FIG. 22D, transmitter coils 2230 a, 2230b, 2230 d, 2230 e, 2230 g, and 2230 h that are positioned amongst theouter transmitter coils can have angular orientations that are eithervertically upward or downward. Transmitter coils 2230 c and 2230 f thatare positioned amongst the inner transmitter coils can have angularorientations that are vertically upward. And, as shown in FIG. 22E,transmitter coils 2232 c, 2232 b, 2232 e, and 2232 f that are positionedamongst the outer transmitter coils can have angular orientations thatare either vertically upward or downward, except for the farthest righttransmitter coil 2232 a when arranged in transmitter coil arrangement2201. Transmitter coils 2232 d and 2232 g that are positioned amongstthe inner transmitter coils can have angular orientations that arevertically upward.

As can be appreciated by FIGS. 22C-E, the outer transmitter coils of atransmitter coil arrangement can be arranged in an angular directionthat are either facing vertically upward or downward, except for thefarthest left and right transmitter coils. And, the inner transmittercoils of a transmitter coil arrangement can be arranged in an angulardirection that is facing in the same direction, e.g., vertically upward.In this manner, the position of termination zones for the transmittercoils in transmitter coil arrangement 2201 can be substantially similarto each other, thereby simplifying design and enhancing chargingefficiency.

Unlike transmitter coils with bobbins that have contact pins that extendbelow a plane of the coil of wire to make contact with the underlyingdriver board, transmitter coils without bobbins can make contact withthe underlying driver board by making contact with surface-mountedstandoffs having contact pads that are elevated from the underlyingdriver board once installed on a driver board. Thus, the contact padscan be positioned in the same plane as the respective transmitter coilsto which they are coupled. Details of such standoffs will be discussedfurther herein.

VI. Wireless Charging Mat Assembly

FIG. 23 illustrates an exploded view of an exemplary wireless chargingmat 2300 having transmitter coils with bobbins, according to someembodiments of the present disclosure. Transmitter coils with bobbinscan correspond to transmitter coils discussed herein with respect toFIGS. 16A-20B. Wireless charging mat 2300 can include a housing formedof two shells: a first shell 2302 and a second shell 2304. First shell2302 can mate with second shell 2304 to form an interior cavity withinwhich internal components may be positioned. Specifically, surfaces offirst and second shells 2302 and 2304 can form walls that define theinternal cavity. For instance, first shell 2302 can have a bottomsurface that forms a first wall defining a top boundary of the internalcavity. Further, second shell 2304 can have a top surface that forms asecond wall defining a bottom boundary of the internal cavity. Sidesurfaces of both first and second shells 2302 and 2304 can havesidewalls that form the lateral boundaries of the internal cavity. Firstand second shells 2302 and 2304 can also include notches 2306 a and 2306b, respectively, that form an opening within the housing when first andsecond shells 2302 and 2304 are mated. An electrical connector 2308,such as a receptacle connector, can be positioned within the opening sothat wireless charging mat 2300 can receive power from an external powersource through a cable connected to electrical connector 2308. In someembodiments, electrical connector 2308 may include a plurality ofcontact pins and a plurality of terminals electrically coupled to thecontact pins so that power can be routed from the external power sourceto the wireless charging mat 2300 to provide power for wireless powertransfer.

First and second shells 2302 and 2304 may each be formed of more thanone layer. For instance, first shell 2302 can include a top covering2310, a compliant layer 2312, and a stiffening layer 2314. In someembodiments, compliant layer 2312 can be disposed between top covering2310 and stiffening layer 2314. Top covering 2310 may be a cosmeticlayer that is exposed when wireless charging mat 2300 is assembled.According to some embodiments, a top surface of top covering 2310includes a charging surface 2316 upon which a device 2340 having awireless power receiver coil 2342 may be placed to receive power fromwireless charging mat 2300. The size and dimensions of charging surface2316 can be defined by one or more transmitter coil arrangements (e.g.,any transmitter coil arrangement discussed herein) encased between firstand second shells 2302 and 2304.

Stiffening layer 2314 can be a rigid structure that gives wirelesscharging mat 2300 structural integrity. Any suitable stiff material maybe used to form stiffening layer 2314 such as fiberglass. Compliantlayer 2312 can be positioned under top covering 2310 to provide a soft,pillow-like texture for devices to rest on when contacting with topcovering 2310 to receive power. Compliant layer 2312 can be formed ofany suitable compliant material, such as a foam or any other porousmaterial.

Second shell 2304 can include a bottom covering 2318, a bottom chassis2320, and a drop frame 2322. In some embodiments, bottom chassis 2320can be positioned between bottom covering 2318 and drop frame 2322.Bottom covering 2318 may be an outer covering that is exposed whenwireless charging mat 2300 is assembled. Bottom chassis 2320 can be astiff structure for providing structural rigidity for wireless chargingmat 2300. In some embodiments, bottom chassis 2320 can be formed of anysuitable stiff materials, such as fiberglass or carbon fiber. Drop frame2322 may be a structural support layer that forms the backbone ofwireless charging mat 2300. In some embodiments, drop frame 2322 is astiff layer of plastic within which a plurality of openings 2348 areformed. Each opening 2348 can be formed to have dimensions correspondingto an electronic device, such as an inverter for operating one or moretransmitter coils, as will be discussed further herein.

As mentioned above, top and bottom shells 2302 and 2304 can mate to forman inner cavity. Several internal components as shown in FIG. 23 can bepositioned within the inner cavity. The internal components may includedetection coils 2324 positioned below first shell 2302. Detection coils2324 can be an arrangement of coils designed to operate at apredetermined frequency that enables detection coils 2324 to detect thepresence of a device positioned on top covering 2310 within chargingsurface 2316.

In some embodiments, the internal components can also include atransmitter coil arrangement 2326 disposed below detection coils 2324.According to some embodiments of the present disclosure, transmittercoil arrangement 2326 can be formed of a plurality of generally planartransmitter coils arranged in multiple layers and in an overlapping andnon-concentric arrangement where no two coils are concentric with eachother. In other words, each transmitter coil can have a central axisthat is positioned a lateral distance away from central axes of allother transmitter coils in the plurality of transmitter coils. Forinstance, transmitter coil arrangement 2326 can include three layers oftransmitter coils (e.g., first layer 2328, second layer 2330, and thirdlayer 2332) where each layer includes a plurality of transmitter coilsthat are arranged coplanar with one another. Some exemplary transmittercoil arrangements include transmitter coil arrangements 800, 1000, 1900,and 2200 in FIGS. 8, 10, 19, and 22 discussed herein above. Transmittercoil arrangement 2326 can be formed of stranded transmitter coils asdiscussed herein with respect to FIGS. 16A-16B and 18A-18B. In someother embodiments, transmitter coil arrangement 2326 can be formed as anarray of patterned conductive wires in a PCB.

Transmitter coil arrangement 2326 can be operated to generatetime-varying magnetic fields that propagate above the top surface offirst shell 2302 to induce a current in receiver coil 2342 in electronicdevice 2340. Coverage of the time-varying magnetic fields generated bytransmitter coil arrangement 2326 may coincide with the dimensions ofcharging surface 2316. In some embodiments, every transmitter coil intransmitter coil arrangement 2326 includes a coil of wire that is woundin the same direction. Receiver coil 2342, on the other hand, caninclude a coil of wire that is wound in the opposite direction as thetransmitter coils. For instance, every coil of wire in transmitter coilarrangement 2326 is wound in a clockwise direction, while the coil ofwire of receiver coil 2342 is wound in a counter-clockwise direction.

In some embodiments, a ferrite layer 2334 can be disposed belowtransmitter coil arrangement 2326. Ferrite layer 2334 may be a layer offerromagnetic material configured to prevent magnetic fields generatedby transmitter coil arrangement 2326 from disrupting components disposedbelow transmitter coil arrangement 2326. Ferrite layer 2334 can be sizedand shaped to correspond to charging surface 2316 and/or to transmittercoil arrangement 2326. In certain embodiments, ferrite layer 2334 can bepositioned directly below first transmitter coil layer 2328. In suchembodiments, first transmitter coil layer 2328 can include coils of wirethat have less turns than the coils of wire in second and thirdtransmitter coil layers 2330 and 2332. Ferrite layer 2334 can include aplurality of openings corresponding to the positions of contacts pins oftransmitter coils in transmitter coil arrangement 2326. The plurality ofopenings allow the transmitter coils to make contact with componentsdisposed below ferrite layer 2334. For instance, the plurality ofopenings can allow the transmitter coils to make contact with a driverboard 2336 disposed below ferrite layer 2334.

Driver board 2336 may be an electrical interconnection structure, suchas a PCB, flex circuit, patterned ceramic board, patterned siliconsubstrate, and the like, configured to route signals and power foroperating transmitter coil arrangement 2326. In some embodiments, driverboard 2336 includes plurality of contacts 2346 positioned to makecontact with corresponding contact pins of transmitter coils intransmitter coil arrangement 2326. A plurality of inverters can bemounted on an underside of driver PCB 2336 for operating the transmittercoils in transmitter coil arrangement 2326. Each inverter can bepositioned at locations corresponding to respective transmitter coilswith which the inverter makes contact. In some embodiments, theplurality of inverters can be surface mounted to the bottom surface ofdriver PCB 2336 such that they extend below driver PCB 2336.Accordingly, the plurality of inverters can insert into respectiveopenings 2348 in drop frame 2322. Openings 2348 can be positioned atlocations corresponding to respective inverters mounted on driver PCB2336. As shown in FIG. 23, notches 2350 may be formed in ferrite layer2334 and driver PCB 2336 for receptacle connector 2308 to be positionedwithin wireless charging mat 2300 when assembled.

In some embodiments, a ground ring 2338 can be wound along at least aportion of the outer perimeter of driver PCB 2336. Ground ring 2338 maybe a conductive wire wound along the outer perimeter of driver PCB 2336except for a location where receptacle connector 2308 is coupled todriver PCB 2336.

FIG. 24 illustrates an exploded view of an exemplary wireless chargingmat 2400 having transmitter coils without bobbins, according to someembodiments of the present disclosure. Transmitter coils without bobbinscan correspond to transmitter coils discussed herein with respect toFIGS. 21 and 22. Like wireless charging mat 2300, wireless charging mat2400 can include a housing formed of two shells: a first shell 2402 anda second shell 2404. First shell 2402 can mate with second shell 2404 toform an interior cavity within which internal components may bepositioned. Similar to wireless charging mat 2300, first and secondshells 2402 and 2404 can also include notches 2406 a and 2406 b,respectively, that form an opening within the housing when first andsecond shells 2402 and 2404 are mated. An electrical connector 2408,such as a receptacle connector, can be positioned within the opening sothat wireless charging mat 2400 can receive power from an external powersource through a cable connected to electrical connector 2408. In someembodiments, electrical connector 2408 may include a plurality ofcontact pins and a plurality of terminals electrically coupled to thecontact pins so that power can be routed from the external power sourceto the wireless charging mat 2400 to provide power for wireless powertransfer.

First and second shells 2402 and 2404 can each be formed of more thanone layer. For instance, first shell 2402 can include a top covering2410 and a stiffening layer 2412. Top covering 2410 can be a cosmeticlayer that is exposed when wireless charging mat 2400 is assembled.According to some embodiments, a top surface of top covering 2410includes a charging surface 2414 upon which a device 2416 having awireless power receiver coil 2415 may be placed to receive power fromwireless charging mat 2400. The size and dimensions of charging surface2416 can be defined by one or more transmitter coil arrangements (e.g.,any transmitter coil arrangement discussed herein) encased between firstand second shells 2402 and 2404.

In some embodiments, top covering 2410 can include a compliant layer(not shown) disposed below charging surface 2414. The compliant layercan be configured to provide a soft, pillow-like texture for devices torest on when contacting with top covering 2410 to receive power. Thecompliant layer can be formed of any suitable compliant material, suchas a foam or any other porous material. Stiffening layer 2414 can bepositioned below top covering 2410, and be composed of a rigid structurethat gives wireless charging mat 2400 structural integrity. Any suitablestiff material may be used to form stiffening layer 2414 such asfiberglass or a stiff polymer (e.g., molded Kalix).

Second shell 2404 can include a bottom covering 2418 and a bottomchassis 2420. In some embodiments, bottom chassis 2420 can be positionedagainst bottom covering 2418 such that bottom chassis 2420 is not shownwhen wireless charging mat 2400 is assembled. Bottom covering 2418 maybe an outer covering that is exposed when wireless charging mat 2400 isassembled. Bottom chassis 2420 can be a stiff structure for providingstructural rigidity for wireless charging mat 2400. In some embodiments,bottom chassis 2420 can be formed of any suitable stiff materials, suchas fiberglass, carbon fiber, or stainless steel.

As mentioned above, top and bottom shells 2402 and 2404 can mate to forman inner cavity. As shown in FIG. 24, various internal components can bepositioned within the inner cavity. For instance, the internalcomponents can include a transmitter coil arrangement 2429. According tosome embodiments of the present disclosure, transmitter coil arrangement2429 can be formed of a plurality of generally planar transmitter coilsarranged in multiple layers and in an overlapping and non-concentricarrangement where no two coils are concentric with each other. Forinstance, transmitter coil arrangement 2429 can include three layers oftransmitter coils (e.g., first layer 2428 a, second layer 2428 b, andthird layer 2428 c) where each layer includes a plurality of transmittercoils that are arranged coplanar with one another. Some exemplarytransmitter coil arrangements include those that have transmitter coilswound about a bobbin, such as transmitter coil arrangements 800, 1000,and 1900 in FIGS. 8, 10, and 19 discussed herein, and those that includetransmitter coils that are not wound about a bobbin, such as transmittercoil arrangement 2200 shown in FIG. 22, discussed herein. Furthermore,transmitter coil arrangement 2429 can have any suitable number oftransmitter coils. For instance, transmitter coil arrangement 2429 canhave a total of 16 coils, such as transmitter coil arrangement 605 inFIG. 6D, or a total of 22 coils, such as transmitter coil arrangement607 in FIG. 6E.

Transmitter coil arrangement 2429 can be operated to generatetime-varying magnetic fields that propagate above the top surface offirst shell 2402 to induce a current in receiver coil 2415 in electronicdevice 2416. Coverage of the time-varying magnetic fields generated bytransmitter coil arrangement 2429 may coincide with the dimensions ofcharging surface 2416.

Wireless charging mat 2400 can also include a plurality of cowlings 2431for housing transmitter coil arrangement 2429. For instance, pluralityof cowlings 2431 can include a first cowling 2430 a, a second cowling2430 b, and a third cowling 2430 c. Each cowling can be a substantiallyplanar structure that has openings 2431 a-c within which transmittercoils can reside. For instance, first cowling 2430 a can house firsttransmitter coil layer 2428 a, second cowling 2430 b can house secondtransmitter coil layer 2428 b, and third cowling 2430 c can house thirdtransmitter coil layer 2428 c. When the transmitter coils are housedwithin the cowling, the cowling can confine the transmitter coils totheir respective positions and prevent them from shifting in any lateraldirection. Some parts of each cowling can also reside within an innerdiameter of transmitter coils to avoid any vacant space within thelayer. Vacant space can allow deflection of structures in adjacentlayers, which can cause physical stress upon one or more components andlead to excessive wear and tear. In some embodiments, the thickness ofeach cowling 2430 a-c is equal to the thickness of a transmitter coil.Thus, when transmitter coils are housed within a respective cowling, thecowling and transmitter coils combine to form a substantially planarstructure that does not have large open spaces within it.

In some embodiments, wireless charging mat 2400 can also include one ormore spacers for separating each layer of transmitter coils andcowlings. For instance, wireless charging mat 2400 can include a firstspacer 2444 a, a second spacer 2444 b, and a third spacer 2444 c. Firstspacer 2444 a can be positioned between first transmitter coil layer2428 a and second transmitter coil layer 2428 b to separate the twotransmitter coil layers 2428 a and 2428 b by a set distance defined bythe thickness of first spacer 2444 a. Similarly, second spacer 2444 bcan be positioned between second transmitter coil layer 2428 b and thirdtransmitter coil layer 2428 c to separate the two transmitter coillayers 2428 b and 2428 c by a set distance defined by the thickness ofsecond spacer 2444 b. Furthermore, third spacer 2444 c can be positionedbetween third transmitter coil layer 2428 c and electromagnetic shield2422 to separate them by a set distance defined by the thickness ofthird spacer 2444 a. In some embodiments, the thickness of spacers 2444a-c are equal such that each transmitter coil layer 2428 a-c andelectromagnetic shield 2422 are separated from each other by the samedistance. One purpose of spacers 2444 a-c is to define a degree ofparasitic capacitance between adjacent conductive layers (e.g.,transmitter coil layers 2428 a-c and electromagnetic shield 2422). Bydefining the space between the conductive layers to be equal, itprovides an increase of sensitivity to detection of foreign objects oncharging surface 2414, specifically in the high frequency range.

During wireless power transfer, transmitter coil arrangement 2429 cangenerate time-varying magnetic fields for inducing a correspondingcurrent in receiver coil 2415. These generated magnetic fields, if notcontrolled, can generate noise and detrimentally affect surroundingcomponents. Thus, transmitter coil arrangement 2429 can be surrounded byseveral components to confine the magnetic fields such that they aregenerated in one direction and do not disturb neighboring components. Insome embodiments, the components include a ferromagnetic shield 2432, anelectromagnetic shield 2422, a grounding fence 2424, and a driver board2426 as will be discussed further herein.

Ferromagnetic shield 2432 can be a layer of ferromagnetic material thatis disposed below transmitter coil arrangement 2429 and configured toprevent magnetic fields generated by transmitter coil arrangement 2429from disrupting components disposed below ferromagnetic shield 2432.Ferromagnetic shield 2432 can be sized and shaped according to chargingsurface 2416 and/or to transmitter coil arrangement 2429. In certainembodiments, ferromagnetic shield 2432 can be positioned directly belowfirst transmitter coil layer 2428 a. In such embodiments, firsttransmitter coil layer 2428 a can include coils of wire that have lessturns than the coils of wire in second and third transmitter coil layers2428 b and 2428 c. Ferromagnetic shield 2432 can include a plurality ofopenings corresponding to the positions of contacts pins of transmittercoils in transmitter coil arrangement 2429. The plurality of openingsallow the transmitter coils to make contact with components disposedbelow ferromagnetic shield 2432, such as driver board 2426.

As mentioned herein, electromagnetic shield 2422 can also be includedwith wireless charging mat 2400. Electromagnetic shield 2422 can bepositioned below first shell 2402 and can be configured to prevent thegeneration of detrimental voltages on a receiver coil during wirelesspower transfer. Particularly, electromagnetic shield 2422 can beconfigured to intercept electric fields generated by transmitter coilswithin wireless charging mat 2400 during wireless power transfer so thatdetrimental voltages are prevented from being generated on a receivercoil, e.g., receiver coil 2415. The structure and material compositionof electromagnetic shield 2422 is discussed further herein with respectto FIGS. 25A and 25B.

FIG. 25A is a top-view illustration of an exemplary electromagneticshield 2500, according to some embodiments of the present disclosure.Electromagnetic shield 2500 can include a shielding body 2502 and aconductive border 2504 around a perimeter of shielding body 2502.Shielding body 2502 can intercept electric fields generated by one ormore transmitter coils in wireless charging mat 2400 and discharge thevoltage generated by the intercepted electric fields to ground throughconductive border 2504. In some embodiments, shielding body 2502 isconstructed of a material having properties that enable magnetic flux topass through the shielding body but prevent electric fields from passingthrough. For instance, shielding body 2502 can be formed of silverlaminated on a layer of pressure sensitive adhesive (PSA). The silverlayer can have a thickness of approximately 30-40 μm, particularly 35 μmin one embodiment. As further shown in FIG. 25A, conductive border 2504can be constructed as a thin conductive region around shielding body2502; however, embodiments are not so limited. Other embodiments canhave different configurations of conductive border 2504, as shown inFIG. 25B.

FIG. 25B is a top-view illustration of another exemplary electromagneticshield 2501, according to some embodiments of the present disclosure.Electromagnetic shield 2501 can include shield body 2502 and aconductive border 2506 that extends to edges of a transmitter coilarrangement, such as any transmitter coil arrangement discussed herein.By extending conductive border 2506 to edges of the transmitter coilarrangement, transmission efficiency of magnetic fields thoroughelectromagnetic shield 2501 can be improved over the transmissionefficiency of electromagnetic shield 2500.

Conductive border 2504 and 2506 can be formed of a conductive material,such as copper. The conductive border 2504 and 2506 can be a thin sheetof copper that is adhered onto the surface of shielding body 2502. Theconductive properties of conductive border 2504 and 2506 allows voltagegenerated by intercepted electric fields to be routed to ground. In someembodiments, conductive border 2504 can route voltage to a groundingfence, such as grounding fence 2424 shown in FIG. 24.

Referring back to FIG. 24 and as aforementioned herein, wirelesscharging mat 2400 can include grounding fence 2424, according to someembodiments of the present disclosure. Grounding fence 2424 can be woundalong at least a portion of the outer perimeter of driver board 2426 andattach to at least a portion of the outer perimeter of electromagneticshield 2422. Grounding fence 2424 can be formed of a length of wirehaving conductive properties, as well as shielding properties to inhibitpropagation of magnetic fields through grounding fence 2422. Forinstance, grounding fence 2422 can be formed of a metal, e.g. steel, ora coated metal, e.g., nickel plated steel.

Driver board 2426 can be a PCB configured to route signals and power foroperating transmitter coil arrangement 2429. In some embodiments, driverboard 2426 can include a plurality of bonding pads 2442 for routingpower to transmitter coil arrangement 2429 via a plurality of standoffs,as will be discussed further herein. Electrical connector 2408 can bemounted on driver board 2426 so that driver board 2426 can receive powerfrom an external source to operate transmitter coil arrangement 2429.The combination of driver board 2426, grounding fence 2424,ferromagnetic shield 2432 and electromagnetic shield 2422 can form afaraday cage that encloses transmitter coil arrangement 2429 to controlthe emission of time-varying magnetic fields generated by transmittercoil arrangement 2429. For instance, the faraday cage can directmagnetic flux out of the faraday cage in a single direction whilesubstantially preventing the propagation of magnetic flux in all otherdirections out of the faraday cage. A better understanding and adifferent perspective of this faraday cage is discussed with respect toand shown in FIGS. 26A and 26B.

FIG. 26A is a cross-sectional view of a part of the faraday cage aroundtransmitter coil arrangement 2429 (not shown) of a partially-formedwireless charging mat, according to some embodiments of the presentdisclosure. It is to be appreciated that transmitter coil arrangement2429 is not shown because only an edge of the faraday cage is shown andthat transmitter coil arrangement 2429 is positioned away from the edgesof the faraday cage, but edges of plurality of cowlings 2431 can beseen. Furthermore, it is to be appreciated that the part of the faradaycage shown in FIG. 26A is only for one side of the wireless charging matand that one skilled in the art understands that this illustration isrepresentative of substantially all edges of a wireless charging mat. Asshown in FIG. 26A, plurality of cowlings 2431 (and transmitter coilarrangement 2429) are enclosed by a faraday cage formed ofelectromagnetic shield 2422, grounding fence 2424, ferromagnetic shield2432, and driver board 2426.

According to some embodiments, the faraday cage can be configured toallow magnetic flux to propagate in one direction. For instance,grounding fence 2424 can be configured to substantially resistpropagation of magnetic flux from transmitter coil arrangement 2429through grounding fence 2424 so that magnetic fields are containedwithin the faraday cage in a lateral direction. Additionally,ferromagnetic shield 2432 can be configured to redirect magnetic flux tosubstantially mitigate the propagation of magnetic flux into driverboard 2426 from transmitter coil arrangement 2429, i.e., downward andout of the faraday cage. However, electromagnetic shield 2422 can beconfigured to allow magnetic flux to propagate through so that themagnetic flux is directed out of the faraday cage in a single direction,e.g., upwards toward a receiver coil in an electronic device. Byconfiguring the faraday cage to allow the propagation of magnetic fluxin one direction, the faraday cage can prevent the generated magneticflux from creating noise in other electrical systems in the wirelesscharging mat while purposefully allowing magnetic flux to propagate in adirection toward a receiver coil to perform wireless charging.

In some embodiments, electromagnetic shield 2422 is attached togrounding fence 2424 so that voltages generated on electromagneticshield 2422 during wireless charging can be discharged to ground. Insome instances, conductive border 2506 of electromagnetic shield 2422 isattached to grounding fence 2424 via laser welding to achieve a robustelectrical and physical connection. Furthermore, ferromagnetic shield2432 can be positioned on a surface of driver board 2426 to mitigate thepropagation of magnetic flux into driver board 2426. In someembodiments, ferromagnetic shield 2432 is positioned on driver board2426 and laterally from grounding fence 2424 such that ferromagneticshield 2432 is not positioned between grounding fence 2424 and driverboard 2426. By not attaching ferromagnetic shield 2432, its brittlestructure will not be exposed to physical stresses at the interfacebetween grounding fence 2424 and driver board 2426, thereby minimizingdamage to ferromagnetic shield 2432.

As mentioned herein with respect to electromagnetic shield 2501 shown inFIG. 25B, conductive border 2506 is adhered to shielding body 2502. Insome embodiments, one or more adhesives can be used to attach conductiveborder 2506 to an edge of shielding body 2502. FIG. 26B is a close-upcross-sectional view of an interface between shielding body 2502 andconductive border 2506. As shown, conductive border 2506 can be attachedto shielding body 2502 by adhesive layers 2602 and 2604. Adhesive layers2602 and 2604 can be any suitable conductive adhesive, such as a singleor double sided copper tape. In some embodiments, adhesive layer 2602 isa layer of double-sided copper tape and adhesive layer 2604 is a layerof single-sided adhesive tape. Using a conductive adhesive allowsvoltage captured on electromagnetic shield 2502 to be routed togrounding fence 2424 through conductive border 2506. Although FIG. 26Billustrates conductive border 2506, it is to be appreciated thatdisclosures herein also apply to embodiments where conductive border2504 is used instead. In some embodiments, shield 2422 can be secured tothird cowling layer 2430 c with an adhesive so that it does notsubstantially move in place during use. For instance, shield 2422 can besecured via an adhesive 2606, such as PSA.

As discussed herein, a driver board can be a PCB configured to operate atransmitter coil arrangement. Thus, with reference back to FIG. 24,driver board 2426 can be electrically coupled to the transmitter coilsin transmitter coil arrangement 2429 via a plurality of standoffs 2434,according to some embodiments of the present disclosure. In someembodiments, each standoff is coupled to a respective bonding pad 2442for enabling power transfer from driver board 2426 to transmitter coilarrangement 2429. Standoffs 2434 can be configured to route powerbetween driver board 2426 and each layer of transmitter coil arrangement2429. For instance, standoffs 2434 can be composed of a plurality ofconductive posts that can route power from one end of the post to anopposite end of the post, as discussed herein with respect to FIGS.27A-B and 28A-B.

FIGS. 27A and 27B illustrate an exemplary standoff 2700, according tosome embodiments of the present disclosure. Standoff 2700 can include afirst contact 2702 on one end and a second contact 2704 on an oppositeend. A connector 2706 can electrically couple first contact 2702 tosecond contact 2704 so that power can be routed between contacts 2702and 2704. In some embodiments, first contact 2702, second contact 2704,and connector 2706 form one monolithic structure that is shaped like theletter “U” tilted on its side. This monolithic structure can have adegree of mechanical compliance when pressure is applied in the verticaldirection. Thus, in some embodiments, first contact 2702, second contact2704, and connector 2706 can be formed of a substantially stiff materialthat is highly conductive, such as a copper alloy with a conductivity ofapproximately 60%-90% of the conductivity of copper. Some exemplarycopper alloys include, but are not limited to, NKC4419, NKE 010, andC19210.

In addition to using mechanically strong conductive materials forforming the monolithic structure, separate support structures can beused to strengthen standoff 2700 as well. For example, a supportcomponent 2708 can be positioned between first and second contacts 2702and 2704 to provide structural support for standoff 2700. Supportcomponent 2708 can also extend over sidewalls of first and secondcontacts 2702 so that only the top surface of first contact 2702 and thebottom surface of second contact 2704 are exposed. To strengthen thestructural coupling between support component 2708 and the monolithicstructure, one or more hook structures can be implemented in firstand/or second contacts 2702 and 2704, as shown in FIG. 28A.

FIGS. 28A and 28B illustrate an exemplary standoff 2800 with hookstructures 2810, according to some embodiments of the presentdisclosure. Like standoff 2700, standoff 2800 can include a firstcontact 2802 and a second contact 2804 that are coupled together viaconnector 2806. First connect 2802, second contact 2804, and connector2806 can form a monolithic structure that is similar to standoff 2700.In some embodiments, standoff 2800 includes hook structures 2810 thatextend from first contact 2802 and/or second contact 2804. As shown inFIG. 28A, hook structures 2810 extend from first contact 2802 and alsoform part of the monolithic structure. Hook structures 2810 provideadditional surface area for making contact with a support structure 2808shown in FIG. 28B to enhance the mechanical coupling with supportstructure 2808.

As discussed herein, standoffs 2434 can be configured to couple driverboard 2426 with each transmitter coil of transmitter coil arrangement2429. Accordingly, standoffs 2434 can be configured to have differentheights to couple driver board 2426 with transmitter coils in differentlayers.

FIG. 29 illustrates an exemplary assembled transmitter coil arrangement2900 attached to an underlying driver board (e.g., driver board 2426)with standoffs 2902, 2904, and 2906. according to some embodiments ofthe present disclosure. Transmitter coil arrangement 2900 can includetransmitter coil 2908 in a first transmitter coil layer, transmittercoil 2910 in a second transmitter coil layer, and transmitter coil 2912in a third transmitter coil layer. Only one transmitter coil from eachlayer of transmitter coil arrangement 2429 is shown in FIG. 29 forclarity purposes.

When assembled, standoffs 2902, 2904, and 2906 can be nested withintransmitter coil arrangement 2900 as shown by the dotted lines. Eachstandoff 2902, 2904, and 2906 can be configured to have a differentheight that corresponds to the respective layer of a transmitter coil towhich it is coupled. For instance, standoff 2902 can have a first heightsuitable for coupling driver board 2426 with transmitter coil 2908 inthe first transmitter coil layer, standoff 2904 can have a second heightsuitable for coupling driver board 2426 with transmitter coil 2910 inthe second transmitter coil layer, and standoff 2906 can have a thirdheight suitable for coupling driver board 2426 with transmitter coil2912 in the third transmitter coil layer. Accordingly, standoff 2906 canbe taller than both standoffs 2902 and 2904, and standoff 2904 can betaller than standoff 2902 but shorter than standoff 2906. Once the threelayers of transmitter coils are assembled, adjacent transmitter coilscan rest against each other yet still couple with driver board 2426,thereby minimizing the z-height of transmitter coil arrangement 2900.

With reference back to FIG. 24, wireless charging mat 2400 can alsoinclude a drop frame 2436 and a bottom shield 2438 for drop frame 2436,according to some embodiments of the present disclosure. When assembledin wireless charging mat 2400, bottom shield 2438 can be adhered to dropframe 2436. Drop frame 2436 can be a structural support layer that formsthe backbone of wireless charging mat 2300. In some embodiments, dropframe 2322 is a stiff layer of plastic within which a plurality ofopenings 2440 are formed. Each opening 2440 can be formed to havedimensions and a position corresponding to one or more electronicdevices, such as a plurality of inverters for operating one or moretransmitter coils, as will be discussed further herein.

FIG. 30 is a bottom-view illustration of drop frame 2436 coupled todriver board 2426, according to some embodiments of the presentdisclosure. The illustration shows drop frame 2436 and driver board 2426without a bottom shield so that the placement of a plurality of packagedelectrical components 3002 can be seen with respect to drop frame 2436.Thus, openings 2440 of drop frame 2436 can allow driver board 2426 to beseen through each opening 2440 when viewed from the bottom-viewperspective. In some embodiments, packaged electrical components 3002,shown as a plurality of black components of various sizes and shapes,can be disposed on driver board 2426 within openings 2440. Electricalcomponents 3002 can be any suitable electrical component utilized foroperating wireless charging mat 2400. For instance, electricalcomponents 3002 can be power electronics, microcontrollers, capacitors,resistors, and the like. In some embodiments, electrical components 3002include a plurality of inverters that can be mounted on a correspondingunderside region of driver board 2426 for operating the transmittercoils in transmitter coil arrangement 2429.

In particular embodiments, some of openings 2440 can provide spacewithin which packaged inverters are disposed to operate an arrangementof transmitter coils, such as arrangement of transmitter coils 605 or607 shown in FIGS. 6D and 6E. For instance, inverter openings 2442 canbe used to provide space in which the packaged inverters are positioned.Inverter openings 2442 are shown with bolded lines so that they areeasier to be seen. In some embodiments, the number of inverter openings2442 for the packaged inverters correspond with the number oftransmitter coils used in the arrangement of transmitter coils. Forinstance, if wireless charging mat incorporates an arrangement oftransmitter coils that is composed of 22 coils, then drop frame 2436 caninclude 22 inverter openings 2442, where each inverter opening providescorresponds with a respective inverter for supporting a respectivetransmitter coil. In some embodiments, inverter openings 2442 aredisposed such that the packaged inverters can be positioned directlybelow respective transmitter coils that they support. In otherembodiments, one or more inverter openings 242 may not be positioned toallow a packaged inverter to be disposed directly below its respectivetransmitter coil. However, these inverter openings nevertheless canallow the packaged inverter to be placed very close to its respectivetransmitter coil and not at an edge of the wireless charging mat whereit is far from its respective transmitter coil. By allowing the packagedinverters to be positioned close to, if not directly below, theirrespective transmitter coils, timing delays and losses caused by highresistances from long trace lengths (as experienced by conventionalcharging mats where inverters are placed at the perimeter of a chargingmat and need to be routed to transmitter coils in the center of thecharging mat) can be minimized.

According to some embodiments of the present disclosure, bottom shield2438 (not shown in FIG. 30) can be laminated on a side of drop frame2436 opposite of the side to which driver board 2426 is coupled. Bottomshield 2438 thus encloses electrical components 3002 within respectiveopenings 2440 so that not only are the electrical components protectedfrom outside electrical disturbances, but that components of wirelesscharging mat 2400 outside of openings 3002 are not disturbed by noisesgenerated from electrical components 3002. In some embodiments, bottomshield 2438 is formed of shielding layer and a plurality of insulatinglayers as shown in FIG. 31.

FIG. 31 is a top-down view of an exemplary bottom shield 3100, accordingto some embodiments of the present disclosure. Bottom shield 3100 caninclude a shielding layer 3102 and a plurality of insulating layers 3104attached to shielding layer 3102. In some embodiments, insulating layers3104 correspond to one or more openings of a drop frame, such asopenings 2440 in FIG. 30. For instance, insulating layers 3104 can beconfigured as strips that correspond to more than one opening 2440/2442,as shown in FIG. 31. When constructed in the wireless charging mat,insulating layer 3104 can be attached to drop frame 2436 and positionedbetween drop frame 2436 (along with its one or more openings) andshielding layer 3102. Insulating layers 3104 can prevent electricalcoupling of electrical components 3002 with the shielding layer 3102. Insome embodiments, shielding layer 3102 is a thin material that isflexible. Thus, areas of shielding layer 3102 directly above openings2440 can deflect into openings 2440 and make contact with one or moreelectrical components 3002. Accordingly, insulating layers 3104 canprevent electrical coupling between shielding layer 3102 and one or moreelectrical components 3002.

Shielding layer 3102 can be formed of any material suitable forshielding against electrical emissions to and from electrical components3002. For instance, shielding layer 3102 can be formed of copper.Insulating layers 3104 can be formed of any electrically insulatingmaterial, such as polyimide.

In some embodiments, a plurality of posts can be disposed withinopenings 2440 to mitigate the degree of travel when shielding layer 3102is depressed into openings 2440. For instance, with reference back toFIG. 30, posts 3004 can be positioned on driver board 2426 in areaswhere there are open spaces to mitigate deflection of bottom shield2438. Additionally, posts 3004 can also prevent electrical components3002 from damage caused by external objects pressing to openings 2440.

VII. Hybrid PCB and Stranded Coil Wireless Charging Mat

According to some embodiments of the present disclosure, a wirelesscharging mat can be configured to provide power to more than onedifferent device. For instance, one device can be a larger device withlarger receiving coils, e.g., a smart phone, table, laptop, and thelike, while the other device can be a smaller device with smallerreceiving coils, e.g., a smart watch, a small portable music player, andthe like. In such embodiments, the wireless charging mat can includemore than one transmitter coil arrangement where each transmitter coilarrangement is optimized for charging a different electronic device.Accordingly, the wireless charging mat can advantageously charge morethan one different device at a time and/or be equally efficient atcharging multiple different devices.

FIG. 30 illustrates an exploded view of an exemplary wireless chargingmat 3200 including more than one transmitter coil arrangement, accordingto some embodiments of the present disclosure. Wireless charging mat3200 can include a first shell 3202 and a second shell 3204, each ofwhich may be constructed similar to first and second shells 2302 and2304 in FIG. 23. First and second shells 3202 and 3204 can mate to forman inner cavity within which internal components can be housed. In someembodiments, the inner cavity can include more than one transmitter coilarrangement. For instance, the inner cavity can include two transmittercoil arrangements: first transmitter coil arrangement 3206 and secondtransmitter coil arrangement 3208. It is to be appreciated that wirelesscharging mat 3200 can further include other internal components similarto wireless charging mat 2320 in FIG. 23 but are not shown for claritypurposes.

First transmitter coil arrangement 3206 may be optimized to charge afirst device 3212 including a first receiver coil 3214 and secondtransmitter coil arrangement 3208 may be optimized to charge a seconddevice 3216 including a second receiver coil 3218 that has a differentsize and shape, and thus different electrical characteristics, than thefirst receiving coil. For example, first device 3212 can be a largerdevice than second device 3216, and first receiver coil 3214 can belarger than second receiver coil 3218. Although each transmitter coilarrangement 3206 and 3208 can be optimized to charge a different device,each transmitter coil arrangement may still charge other devices thatthey are not optimized to charge but in a less efficient manner. It isto be appreciated that even though FIG. 30 illustrates only two devices,embodiments discussed herein may be configured to charge more than twodevices, each having different sizes and shapes than those shown in FIG.30. Furthermore, it is to be appreciated that each transmitter coilarrangement can charge an electronic device across the entire chargingsurface. It is not the case where one transmitter coil arrangement canonly charge devices in a sub-region of the charging surface, and thatthe other transmitter coil arrangement can only charge devices inanother sub-region of the charging surface.

In some embodiments, first and second transmitter coil arrangements 3206and 3208 can be formed of transmitter coils where the sizes of thetransmitter coils are optimized for a different electrical device. As anexample, first transmitter coil arrangement 3206 can be formed oftransmitter coils of a first size, while second transmitter coilarrangement 3208 is formed of transmitter coils of a second size. Thefirst size can correspond to the size of receiver coil 3214 in firstelectronic device 3212, whereas the second size can correspond to thesize of receiver coil 3218 in second electronic device 3216.Accordingly, first transmitter coil arrangement 3206 may be particularlyefficient at inducing a current in receiver coil 3214 of first device3212 but less efficient at inducing a current in receiver coil 3218 ofsecond device 3216. Conversely, second transmitter coil arrangement 3208may be particularly efficient at inducing a current in receiver coil3218 of second device 3216 but less efficient at inducing a current inreceiver coil 3214 of first device 3212. It is to be appreciated thateach transmitter coil arrangement can charge an electronic device acrossthe entire charging surface.

In additional embodiments, first and second transmitter coilarrangements 3206 and 3208 can be arranged in different patterns whereeach pattern is optimized for a different electrical device. As anexample, first transmitter coil arrangement 3206 can be arranged in asingle row of transmitter coils, while second transmitter coilarrangement 3208 is arranged according to any of transmitter coilarrangements 800, 1000, 1900, and 2200 in FIGS. 8, 10, 19, and 22discussed herein above. Accordingly, first transmitter coil arrangement3206 may be particularly efficient at inducing a current in receivercoil 3214 of first device 3212 but less efficient at inducing a currentin receiver coil 3218 of second device 3216, and vice versa.

As discussed herein, transmitter coil arrangements can generatetime-varying magnetic fields. Thus, first and second transmitter coilarrangements 3206 and 3208 can be operated at various frequencies togenerate the time-varying magnetic fields. In some embodiments, firsttransmitter coil arrangement 3206 can operate at a first frequency whilesecond transmitter coil arrangement 3208 operates at a second frequency.The first and second frequencies may be the same or different when firstand second transmitter coil arrangements 3206 and 3208 are arranged indifferent patterns. However, the first and second frequencies aredifferent when first and second transmitter coil arrangements 3206 and3208 are arranged in the same pattern. For instance, first and secondtransmitter coil arrangements 3206 and 3208 can both be arrangedaccording to any of transmitter coil arrangements 800, 1000, 1900, and2200 in FIGS. 8, 10, 19, and 22 discussed herein above, or any othertransmitter coil arrangement. In such cases, first transmitter coilarrangement 3206 may operate at a frequency that is particularlyefficient at inducing a current in receiver coil 3214 of first device3212 but less efficient at inducing a current in receiver coil 3218 ofsecond device 3216. Conversely, second transmitter coil arrangement 3208can operate at a frequency that is particularly efficient at inducing acurrent in receiver coil 3218 of second device 3216 but less efficientat inducing a current in receiver coil 3214 of first device 3212. Thedifference in operating frequencies may depend on the particularoperating frequencies of the respective receiver coils. In someembodiments, the difference can range between orders of magnitudes. Asan example, the first frequency can be an order of one or two magnitudeshigher than the second frequency. In particular embodiments, the firstdevice 3212 is a smart watch and second device 3216 is a smart phone.

Furthermore, in some embodiments, first and second transmitter coilarrangements 3206 and 3208 can be formed from the same or differenttransmitter coils. That is, first transmitter coil arrangement 3206 canbe formed from transmitter coils having stranded coiled wire with orwithout bobbins, e.g., transmitter coils 1600, 1800, and 2100 in FIGS.16, 18, and 21, while second transmitter coil arrangement 3208 can beformed within a PCB. Each form of construction can be tailored toefficiently induce power in a respective device. For instance, thestranded coil construction of second transmitter coil arrangement 3208may be particularly efficient at inducing a current in receiver coil3218 of second device 3216 but less efficient at inducing a current inreceiver coil 3214 of first device 3212.

Although the invention has been described with respect to specificembodiments, it will be appreciated that the invention is intended tocover all modifications and equivalents within the scope of thefollowing claims.

What is claimed is:
 1. An electronic device, comprising: a housingcomprising a charging surface; and an inductor coil arrangement disposedwithin the housing, the inductor coil arrangement comprising: a firstinductor coil layer in a first plane including a first inductor coilhaving a first center axis; a second inductor coil layer in a secondplane including a second inductor coil overlapping with a portion of thefirst inductor coil and having a second center axis; a third inductorcoil layer in a third plane including a third inductor coil overlappingwith a portion of the first inductor coil and a portion of the secondinductor coil, the third inductor coil having a third center axis,wherein the first center axis, the second center axis, and the thirdcenter axis are equally spaced apart from one another; and a spacinglayer between one of the first inductor coil layer and the secondinductor coil layer or the second inductor coil layer and the thirdinductor coil layer, wherein the spacing layer defines a degree ofparasitic capacitance between adjacent conductive layers.
 2. Theelectronic device of claim 1, wherein the first center axis is laterallypositioned outside of a first outer diameter of the second inductor coiland the third inductor coil, the second center axis is laterallypositioned outside of a second outer diameter of the first inductor coiland the third inductor coil, and the third center axis is laterallypositioned outside of a third outer diameter of the first inductor coiland the second inductor coil.
 3. The electronic device of claim 1,wherein the first center axis, the second center axis, and the thirdcenter axis are arranged in an equilateral triangle pattern.
 4. Theelectronic device of claim 1, wherein the inductor coil arrangement isformed with a total of three inductor coils.
 5. The electronic device ofclaim 1, wherein the first inductor coil layer further includes a fourthinductor coil and a fifth inductor coil, and the second inductor coillayer further includes a sixth inductor coil and a seventh inductorcoil.
 6. The electronic device of claim 5, wherein the first inductorcoil, the fourth inductor coil, and the fifth inductor coil in the firstinductor coil layer are coplanar, equally spaced apart from one other,and positioned in a non-overlapping arrangement.
 7. The electronicdevice of claim 5, wherein the second inductor coil, the sixth inductorcoil, and the seventh inductor coil in the second inductor coil layerare coplanar, equally spaced apart from one other, and positioned in anon-overlapping arrangement.
 8. The electronic device of claim 5,wherein the third inductor coil overlaps with a portion of all otherinductor coils in the inductor coil arrangement.
 9. The electronicdevice of claim 5, wherein the third center axis is positioned at acenter of an entire inductor coil arrangement.
 10. The electronic deviceof claim 5, wherein the inductor coil arrangement is formed with a totalof seven inductor coils.
 11. A wireless charging device, comprising: ahousing comprising a charging surface; and an inductor coil arrangementdisposed within the housing, the inductor coil arrangement comprising: afirst inductor coil layer in a first plane including a first inductorcoil having a first center axis; a second inductor coil layer in asecond plane including a first plurality of inductor coils arranged in anon-overlapping arrangement with one another and in an overlappingarrangement with the first inductor coil, wherein each inductor coil ofthe first plurality of inductor coils are spaced equally apart from oneanother; a third inductor coil layer in a third plane including a secondplurality of inductor coils arranged in a non-overlapping arrangementwith one another and in an overlapping arrangement with the firstinductor coil, wherein each inductor coil of the second plurality ofinductor coils are spaced equally apart from one another; and a spacinglayer between one of the first inductor coil layer and the secondinductor coil layer or the second inductor coil layer and the thirdinductor coil layer, wherein the spacing layer defines a degree ofparasitic capacitance between adjacent conductive layers.
 12. Thewireless charging device of claim 11, wherein the first plurality ofinductor coils includes three inductor coils, wherein each inductor coilof the first plurality of inductor coils includes a center axis that isequally spaced apart from the center axes all other inductor coils inthe second inductor coil layer.
 13. The wireless charging device ofclaim 12, wherein the second plurality of inductor coils includes threeinductor coils, wherein each inductor coil of the second plurality ofinductor coils includes a center axis that is equally spaced apart fromthe center axes all other inductor coils in the second inductor coillayer.
 14. The wireless charging device of claim 13, wherein the firstcenter axis is equally spaced apart in a lateral dimension from a centeraxis of all other inductor coils in the second inductor coil layer andthe third inductor coil layer of the inductor coil arrangement.
 15. Thewireless charging device of claim 11, wherein the first inductor coiloverlaps with a portion of all other inductor coils in the inductor coilarrangement.
 16. A wireless charging system, comprising: a firstelectrical device comprising a receiver coil configured to generate acurrent to charge a battery when exposed to a time-varying magneticflux; and a second electrical device configured to generate thetime-varying magnetic flux to wirelessly charge the first electricaldevice, the second electrical device comprising: a housing comprising acharging surface; and an inductor coil arrangement disposed within thehousing, the inductor coil arrangement comprising: a first inductor coillayer in a first plane including a first inductor coil having a firsttermination zone at a center of the first inductor coil; a secondinductor coil layer in a second plane including a second inductor coiloverlapping with a portion of the first inductor coil and having asecond termination zone at a center of the second inductor coil; and athird inductor coil layer in a third plane including a third inductorcoil overlapping with a portion of the first inductor coil and a portionof the second inductor coil, the third inductor coil having a thirdtermination zone at a center of the third inductor coil; and a spacinglayer between one of the first inductor coil layer and the secondinductor coil layer or the second inductor coil layer and the thirdinductor coil layer, wherein the spacing layer defines a degree ofparasitic capacitance between adjacent conductive layers.
 17. Thewireless charging system of claim 16, wherein a first center axis islaterally positioned outside of a first outer diameter of the secondinductor coil and the third inductor coil, a second center axis islaterally positioned outside of a second outer diameter of the firstinductor coil and the third inductor coil, and a third center axis islaterally positioned outside of a third outer diameter of the firstinductor coil and the second inductor coil.
 18. The wireless chargingsystem of claim 16, wherein a first center axis, a second center axis,and a third center axis form an equilateral triangle.
 19. The wirelesscharging system of claim 16, wherein the inductor coil arrangement isformed with a total of three inductor coils.
 20. The wireless chargingsystem of claim 16, wherein the first inductor coil layer furtherincludes a fourth inductor coil and a fifth inductor coil, and thesecond inductor coil layer further includes a sixth inductor coil and aseventh inductor coil.